Article

https://doi.org/10.1038/s41467-024-48628-z

An inorganic-blended p-type semiconductor
with robust electrical and mechanicalproperties
Received: 1 August 2023

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Accepted: 6 May 2024

You Meng 1,2,8, Weijun Wang1,8, Rong Fan3,4,8, Zhengxun Lai1, Wei Wang1,
Dengji Li1, Xiaocui Li 3, Quan Quan1, Pengshan Xie1, Dong Chen1, He Shao1,
Bowen Li1, Zenghui Wu1, Zhe Yang5, SenPo Yip6, Chun-Yuen Wong 5 ,Yang Lu 4,7 & Johnny C. Ho 1,2,6

Inorganic semiconductors typically have limited p-type behavior due to thescarcity of holes and the localized valence band maximum, hindering the
progress of complementary devices and circuits. In this work, we propose an
inorganic blending strategy to activate the hole-transporting character in an
inorganic semiconductor compound, namely tellurium-selenium-oxygen(TeSeO). By rationally combining intrinsic p-type semimetal, semiconductor,
and wide-bandgap semiconductor into a single compound, the TeSeO system
displays tunable bandgaps ranging from 0.7 to 2.2 eV. Wafer-scale ultrathin
TeSeO ﬁlms, which can be deposited at room temperature, display high holeﬁeld-effect mobility of 48.5 cm2/(Vs) and robust hole transport properties,
facilitated by Te-Te (Se) portions and O-Te-O portions, respectively. The
nanosphere lithography process is employed to create nanopatterned honeycomb TeSeO broadband photodetectors, demonstrating a high responsibility of 603 A/W, an ultrafast response of 5 μs, and superior mechanicalﬂexibility. The p-type TeSeO system is highly adaptable, scalable, and reliable,
which can address emerging technological needs that current semiconductor
solutions may not fulﬁll.

Semiconducting properties are present in numerous elements andcompounds. Some examples of pure elements are found in group 14,
such as the commercially important C1, Si2, and Ge3, which are connected by covalent bonds. By sharing their outermost (valence) electrons to form a full electron shell, the stable balance of attractive/
repulsive forces among atoms allows them to attain stable electronic
conﬁguration. Nonetheless, covalent bonding relies heavily on the
directional nature of atomic orbitals, imposing substantial constraints

on the design of covalent compounds. For instance, it only takes 4%
lattice constant mismatch to make the Si-Ge system strained andpossibly metastable4,5. Moreover, owing to their stable crystal structures and chemically unreactive properties, producing high-quality
covalent semiconducting materials invariably requires hightemperature growth (600 °C or higher) and subsequent annealing
procedures6,7. These factors limit the feasibility of tuning the bandgap
and the ﬂexible integration of covalent semiconductors.

1

Department of Materials Science and Engineering, City University of Hong Kong, Kowloon 999077, Hong Kong SAR. 2State Key Laboratory of Terahertz andMillimeter Waves, City University of Hong Kong, Kowloon 999077, Hong Kong SAR. 3Department of Mechanical Engineering, City University of Hong Kong,
Kowloon 999077, Hong Kong SAR. 4Chengdu Research Institute, City University of Hong Kong, Chengdu 610200, China. 5Department of Chemistry, City
University of Hong Kong, Kowloon 999077, Hong Kong SAR. 6Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 816 8580, Japan.
7
Department of Mechanical Engineering, The University of Hong Kong, Pokfulam 999077, Hong Kong SAR. 8These authors contributed equally: You Meng,
Weijun Wang, Rong Fan.
e-mail: acywong@cityu.edu.hk; ylu1@hku.hk; johnnyho@cityu.edu.hk

Nature Communications | (2024)15:4440

1

Articlehttps://doi.org/10.1038/s41467-024-48628-z

On the other hand, with sharply different electronegativities, theelectrostatic attraction between oppositely charged ions could form
ionic or polar covalent bonds. Compound semiconductors made bythese two types of chemical bonds, primarily comprising transitionmetal cations from group 10–14, have been identiﬁed to possess
respectable electron mobility, i.e., tens of cm2/(Vs) for amorphous/polycrystalline and hundreds of cm2/(Vs) for crystalline ones8–10.
However, despite extensive efforts over many years, the inferior holemobility exhibited by their p-type counterparts has hindered theprogress of complementary devices and circuits. The main causes fortheir poor p-type performance include the localized valence band
maximum (VBM), strong self-compensation effect, and poor material
stability8,11,12. For instance, in p-type transition-metal oxides (halides)
such as CuOx, SnO, and CuI, high concentrations of oxygen (halogen)vacancies typically function as compensating intrinsic defects that
capture holes, thereby impeding their hole transport13,14. To bypass
these ingrained issues, an alternative material design strategy is
expected to explore better p-type semiconductors.
In this work, a high-mobility and air-stable p-type semiconducting
system, namely tellurium-selenium-oxygen (TeSeO), was exploredbased on an inorganic blending strategy (Fig. 1a). Group 16 elements,
i.e., Te, Se, and O, are utilized because of their similar s2p4 electronica

conﬁgurations and atomic radii, which endows good miscibility toform the TeSeO system. Due to the different ionization energy andelectronegativity, the metallic characters of elements become more
pronounced as one moves down group 16, which spans from insulator
to semiconductor to metalloid. This variation allows for continuous
tuning of the physical properties of the TeSeO system through different compositions. In particular, semimetal Te has high intrinsic holemobility (~105 cm2/Vs) and small effective hole mass (~0.3 m0)15,16,
which is covalently bonded as Te–Te or Te–Se that mainly contributes
to the good hole-transport property. Semiconducting Se is used toeffectively modify the bandgap (from 0.7 to 2.2 eV), oxidative ability,
and crystallinity of TeSeO to meet technical requirements. Notably, theemployment of O forms O–Te–O (polar covalent bonds) with a wider
bandgap17,18, endowing superior operating durability to TeSeO that isunachievable by other p-type thin-ﬁlm semiconductors.

Results
TeSeO synthesis and microstructure characterization
To satisfy the scalable processing, in this work, TeSeO thin ﬁlms were
produced by room-temperature physical vapor deposition (PVD)
combined with post-oxygen implantation (details shown in the Methods section). The crystal structures of TeSeO thin ﬁlms were

b

c TeO

Te0.3Se0.7O0.15

1.16

Se

Group 16
(ns2np4)

Te0.1Se0.9O0.04
Te0.2Se0.8O0.09
Te0.3Se0.7O0.15

EN = 3.44

Polarcovalentbond

Te0.4Se0.6O0.23

Intensity (a.u.)

Se

Te0.7Se0.3O0.59

Te0.5Se0.5O0.32
Te0.6Se0.4O0.44
Te0.7Se0.3O0.59

Covalent EN = 2.55
bond

Te0.8Se0.2O0.8

2.0

Te0.5Se0.5O0.32

Roughness (nm)

No
bond

3 m

Te0.9Se0.1O0.98
TeO1.16

1 cm

EN = 2.12

30

40

e

2 nm

0.8
0.4

5 1/nm

Te0.7Se0.3O0.59

(102)
(201)
(211)

Fig. 1 | TeSeO synthesis and microstructure characterization. a Schematic of
p-type TeSeO semiconducting system containing group 16 elements. b GIXRD
patterns and c AFM images of TeSeO thin ﬁlms with different compositions. Insets
of b display the corresponding sample photographs. Inset of c shows the

Nature Communications | (2024)15:4440

5 1/nm

9

2

5

.3
.5
6
.1
O 1.1 e 0.3O 0 e 0.5O 0 e 0.7O 0 Se
Te
S
S
S
.5
.7
Te 0 Te 0.3
Te 0

50

(polycrystalline+ amorphous)(polycrystalline)

TeO1.16

Rq
Ra

1.2

0.0

20

2 theta (degree)d

1.6(amorphous)
Te0.5Se0.5O0.32

(100)
(201)
(202)

amorphous rings
5 1/nmcorresponding roughness values of TeSeO thin ﬁlms based on root-mean-squaredeviation (Rq) and arithmetic-mean deviation (Ra). d Cross-sectional HRTEM imageof Te0.7Se0.3O0.59 thin ﬁlm. e SAED patterns of TeO1.16, Te0.7Se0.3O0.59, andTe0.5Se0.5O0.32 thin ﬁlms.

2Articlehttps://doi.org/10.1038/s41467-024-48628-z

characterized by a grazing-incidence x-ray diffractometer (GIXRD). As
shown in Fig. 1b, the TeSeO samples with relatively high Te content(Te:Se ≥ 7:3) show a polycrystalline nature, while the Se-rich samples(Te:Se ≤ 6:4) are found to be amorphous. The diffraction peaks locatedat 23.1, 27.6, 40.5, and 49.7° agree well with those of (100), (101), (110),and (201) planes, respectively, of hexagonal system with P3121 [152]space group that is composed of chalcogen chains along the c axis17. All
the diffraction peak positions slightly shift to higher angles withincreasing Se content (Supplementary Fig. 1), indicating the decreaseof the lattice constant. At the same time, the increased full width at
half-maximum of the diffraction peaks also reveals the suppressedmaterial crystallinity. As a strong glass former, the further addition of
Se contents (Te:Se ≤ 6:4) completely disturbs the crystallization process of TeSeO, leading to the polycrystalline-to-amorphous phasetransition. Remarkably, with the vigorous compositional changing of
TeSeO thin ﬁlms, the samples undergo signiﬁcant color changes frommetallic luster for TeO1.16 to dark red for Se-rich samples, as the photographs depicted in the insets of Fig. 1b.
The Raman spectroscopy presented in Supplementary Fig. 2
identiﬁed three ﬁrst-order Raman active Te/Se helical chain modes,
including E1 transverse (TO) phonon mode, A1 mode, and E2 mode16.
Also, Se substituted for Te gives rise to an increase in the stretchingfrequency and the broadening of Raman bands. The undiscovered
O-related Raman vibrations suggest the disordered nature of corresponding oxides that cannot efﬁciently enable the inelastic scatteringof photons. To directly check the elemental distribution, a combination of energy-dispersive X-ray spectroscopy (EDS) mapping and X-ray
photoelectron spectroscopy (XPS) were conducted on TeSeO thinﬁlms (Supplementary Figs. 3 and 4), where the uniform elemental
distributions of Te, Se, and O are observed across the probed region.
Moreover, the surface morphologies of TeSeO thin ﬁlms with different
composition ratios were examined by atomic force microscopy (AFM)with a scanning area of 10 × 10 μm (Fig. 1c). All the TeSeO thin ﬁlms aresmooth, uniform, and crack-free, which is crucial for practical devices.
The extracted arithmetic-mean deviation of roughness decreases from
1.8 nm to 0.3 nm with increasing Se content (inset of Fig. 1c), mainly
due to the decreasing grain sizes.
The microscopic structures of the TeSeO thin ﬁlms were further
analyzed by cross-sectional high-resolution transmission electron
microscopy (HRTEM), as depicted in Fig. 1d. The HRTEM image shows
clear lattice fringes with lattice spacings of 3.2 Å and 2.2 Å for crystalline
Te0.7Se0.3O0.59, which corresponds to the (1011) and (1120)
planes of hexagonal Te/Se, respectively. The corresponding selectedarea electron diffraction (SAED) pattern of Te0.7Se0.3O0.59 shows a few
diffraction spots (Fig. 1e), further indicating its polycrystalline structure. The observed characteristic diffuse halo, particularly evident inTe0.5Se0.5O0.32, indicates that the addition of Se induces apolycrystalline-to-amorphous phase transition in TeSeO. Overall, noO-related phase diffraction pattern was detected in the SAED study,
suggesting an amorphous state of oxides in TeSeO. The above
microstructure analysis agrees well with that from XRD and Raman
studies.

60 eV) peak is found from Se 3d spectra in Fig. 2c, mainly owing to its
larger electronegativity (2.55) than that of Te (2.1), which make it difﬁcult to react with oxygen molecules to form SeO2. The distinct peaks
observed around 530.2 eV in the O 1 s spectra imply the O mainly acts
as lattice oxygen species of O–Te–O (Fig. 2b and Supplementary
Fig. 6). Generally, the adsorbed oxygen or hydroxyl group has higher
binding energy around 532 eV10, which is not witnessed in our TeSeO
ﬁlms. The gathered information on chemical bonding in inorganicblended TeSeO, including Te-Te, Te-Se, and O-Te-O, is summarized inTable 1. Overall, the Se-regulating Te oxidation provides a window tochange the material compositions among TeO2 (p-type wide-bandgap
semiconductor)19,20, TexSey (p-type semiconductor)21,22, and Te (p-type
semimetal)16,17, and thus modify their corresponding physical/chemical
properties in a wide range.
In general, continuously tuning bandgaps and band-edge energies
in conventional p-type semiconductors is difﬁcult13. Apart from the low
formation energy of the electron donor, incorporating foreign atoms
could inevitably perturb the host lattice thermodynamic equilibrium,
possibly counteracting the p-doping effect14. These factors restrict thetuning feasibility on hole density and mobility of conventional p-typethin ﬁlms. This work applies an inorganic blending strategy on thep-type TeSeO system, which combines intrinsic p-type semimetal,
semiconductor, and wide-bandgap semiconductor in a single compound. As a result, the p-type TeSeO could be manufactured intoa scalable thin-ﬁlm form with reliable and tunable material properties.
As presented in Fig. 2d, the optical bandgaps of TeSeO thin ﬁlms wereextracted from the absorption spectra by using the Tauc plot method.
With increasing Se content, the energy bandgaps of TeSeO werebroadening, with corresponding bandgap values monotonically shifting from 0.7 eV to 2.2 eV. The continuously tunable bandgaps achieved
from TeSeO thin ﬁlms cover ultraviolet (UV), visible, and short-wave
infrared (SWIR) regions, revealing potentials in high-mobility p-channel transistors, solar cells, wideband photodetectors, etc.
The quantitatively predictable and available band structures of
the TeSeO system are the prerequisite for device-level engineering. To
this aim, the electronic structure variations of TeSeO thin ﬁlms wereidentiﬁed by ultraviolet photoemission spectroscopy (UPS). The
positions of Fermi energy levels and VBM levels could be extracted
from the secondary electron cut-off region (Fig. 2e) and valence-band
region (Fig. 2f), respectively23. Besides, the conduction band minimum(CBM) was calculated by subtracting the bandgap of each sample fromits VBM. The corresponding energy band diagrams of TeSeO samples
are presented in Fig. 2g. Obviously, for all TeSeO samples, their Fermi
energy levels are always underlying the mid-point of bandgaps andrelatively close to the valance band, which means that the inorganicblended TeSeO system keeps p-type electrical properties. It is also
found that the energy level of the VBM shifts faster with compositions
than that of CBM. Fitting these results to the modiﬁed Vegard’s law, theenergy changes of VBM energies are nearly linear with the composition, while the CBM energies change with a strong bowing of ~1 eV. This
result could be explained by the synergistic effect of Se substitution
and partly oxidation in Te22.

Chemical bonding and band structure of TeSeO

Transport properties and electrical robustness of TeSeO

To obtain the details of chemical bonding and atomic coordination in
TeSeO thin ﬁlms, core energy level spectra of Te 3d, O 1s, and Se 3dwere studied using XPS (Fig. 2a–c). All three XPS core energy levels of
TeSeO exhibit redshifts of up to 800 meV with increasing Se content,
resulting from the electron injection process. In detail, the Te4+ and Te0
peaks coexist in the Te 3d spectra of TeSeO thin ﬁlms (Fig. 2a), whichmeans the partial oxidation of Te18. The corresponding Te4+/(Te0++Te4+) ratios decrease from ~58% (TeO1.16) to ~25% (Te0.3Se0.7O0.15)
with increasing Se content (Supplementary Fig. 5 and Supplementary
Table 1), revealing that the Se content could suppress the binding
process between Te and O. At the same time, no Se4+ (typically aroundTo investigate the hole-transport properties of TeSeO thin ﬁlms, aseries of bottom-gate top-contact (BGTC) thin-ﬁlm transistors (TFTs)
are constructed on SiO2/p+-Si wafers with Ni as source/drain electrodes. To guarantee low gate leakage currents and reliable parameter
extraction, both channel layers and electrodes are patterned (inset in
Fig. 3a). The channel thickness of ~10 nm, which is veriﬁed by crosssectional STEM, is used to balance the conductivity and the on/off
current ratio. As the corresponding electrical characteristics of
Te0.7Se0.3O0.59, Te0.8Se0.2O0.8, and Te0.9Se0.1O0.98 are shown in Fig. 3,
typical p-channel transistor behaviors were observed for those devices, agreeing well with their energy band structures. The Se-poor

Nature Communications | (2024)15:4440

3

Article

Te0.5Se0.5O0.32

Te0.7Se0.3O0.59

Te

0

TeO1.16

570

575

Te0

580

Te

Te0.3Se0.7O0.15

Te0.5Se0.5O0.32
Te0.7Se0.3O0.59

585

590

526

528

Te0.5Se0.5O0.32
Se0 Se0Te0.7Se0.3O0.59
TeO1.16

TeO1.16
Te0.7Se0.3O0.59
Te0.5Se0.5O0.32
Te0.3Se0.7O0.15
Se

2.0

530

532

534

TeO1.16
Te0.7Se0.3O0.59
Te0.5Se0.5O0.32
Te0.3Se0.7O0.15
Se

Intensity (a.u.)

Absorption (a.u.)

Te0.3Se0.7O0.15

52

2.5

14.0 14.5 15.0 15.5 16.0 16.5

Photon energy (eV)

54

56

58

Binding energy (eV)Binding energy (eV)

e

1.5

Se

TeO1.16

d

1.0

Se 3d

O-Te-O

4+

Binding energy (eV)

0.5

c

Se

Intensity (a.u.)

Te0.3Se0.7O0.15

Te4+

O 1s

Intensity (a.u.)

b

Se

f

TeO1.16
Te0.7Se0.3O0.59
Te0.5Se0.5O0.32
Te0.3Se0.7O0.15
Se

Log Intensity (a.u.)

Te 3dIntensity (a.u.)ahttps://doi.org/10.1038/s41467-024-48628-z-1

Binding energy (eV)

0

1

2

3

Binding energy (eV)Energy (eV)

g -4
CBM

-5

Mid-Eg
EF

-6

-7

-8

VBM

TeO1.16

Te0.7Se0.3O0.59

Te0.5Se0.5O0.32 Te0.7Se0.3O0.15

Fig. 2 | Chemical bonding and band structure of TeSeO. XPS (a) Te 3d, b O 1s, andc Se 3d analysis of TeSeO thin ﬁlms with different compositions. d Absorption
spectra of the prepared ﬁlms with different compositions. UPS spectra of TeSeO

Se

thin ﬁlms at e secondary electron cut-off regions and f valence-band regions.
g Energy band diagram of the TeSeO thin ﬁlms with changing compositions.

Table 1 | The chemical bonding information of inorganic-blended TeSeO
Bond

Type

Bandgap

Character

Function

Te–Te

Covalent

0.31 eVp-type semimetalHigh hole mobility

Te–Se

Covalent

0.31~1.87 eV

p-type semiconductor

Bandgap modulation

O–Te–O

Polar covalent

3.7 eVp-type wide-bandgap semiconductor

Stability enhancement

Te0.9Se0.1O0.98 TFT exhibited high conductance and “always-on”
transistor operation, which reﬂected high hole concentration in thechannel layer that could not be completely depleted23. The Se
alloying reduced the current level and mobility and shifted thresholdvoltage (VTH) in the negative direction (Fig. 3d–f). Meanwhile, theHall effect measurements of TeSeO ﬁlms show a similar trend to theelectrical properties observed in the TFTs study (Supplementary
Table 2).

Nature Communications | (2024)15:4440

Notably, among all the samples, the Te0.8Se0.2O0.8 TFT showed
well-optimized electrical performance (Fig. 3e), including a high holeﬁeld-effect mobility (μFE) of 48.5 cm2/(Vs) while maintaining a high Ion/
Ioff ratio of ~105. As summarized in Table 2 and Supplementary Table 3,such μFE and Ion/Ioff surpass most previously reported conventional
scalable p-channel TFTs, including metal oxides, metal halides, perovskite halides, and organic materials11. Besides, the negligible counterclockwise hysteresis indicates the small amounts of electrical traps
4Articlehttps://doi.org/10.1038/s41467-024-48628-z

Vgs = 20 V

-5

Source Drain
Channel

-10
-15

-0.05

0.00

0

Vgs = 20 V

-25
-50

100 m
-0.10

25

0.05

0.10

Vds = - 0.1 V

75
10-6

10-8
10

50

Vds = - 0.01 V

Te0.7Se0.3O0.59
25

-9

e 10
Drain Current (A)Drain Current (A)

100

10-7

-10

0

Vgs = 20 V

0
-20
-40
-60

-0.10

10

-0.05

0.00

0.05

-100

0.10

-0.10

20

f

-4

100

10-5
75
10-6
10-7

Vds = - 0.01 V

Te0.8Se0.2O0.8

50

10-8

25

-9

0

Gate Voltage (V)

-10

0

10

Gate Voltage (V)

0.00

10-4

0.05

0.10

20

0

Vds = - 0.1 V

100

10-5
75
10-6

Vds = - 0.01 V

50

10-7
10-8
10

-20

-0.05

Drain Voltage (V)Vds = - 0.1 V

10
-20

20

Drain Voltage (V)

-4

10-5

40

-80
-75

Drain Voltage (V)

d10

60

Vgs = -20 V

Te0.9Se0.1O0.98

Te0.9Se0.1O0.98

-9

-20

-10

0

10

20

25

Hole Mobility (cm2/Vs)

080

Te0.8Se0.2O0.8

Drain Current (A)Drain Current ( A)

5

50

c 100

Vgs = -20 V

Drain Current ( A)Te0.7Se0.3O0.59

10

b 75

Vgs = -20 V

Drain Current ( A)

a 15

0

Gate Voltage (V)gFig. 3 | Transport properties and electrical robustness of TeSeO. Output curvesof a Te0.7Se0.3O0.59, b Te0.8Se0.2O0.8, and c Te0.9Se0.1O0.98 TFTs. Inset of a shows the
optical image of the device. Transfer curves and hole mobilities of d Te0.7Se0.3O0.59,

e Te0.8Se0.2O0.8, and f Te0.9Se0.1O0.98 TFTs. g On/off switching measurements of
Te0.8Se0.2Ox and Te0.8Se0.2 TFTs. Inset of g shows the representative on/off
switching cycles.

within TeSeO or at the interface between the channel and dielectric
layers24. To study the scalability and uniformity of TeSeO TFTs, waferscale TFT arrays (10 × 10 array) are fabricated, and their statistical
distribution of device performance is displayed in Supplementary
Fig. 7. The TFT array shows 100% device yield with a hole mobility of
48.2 ± 8.4 cm2/(Vs), Ion/Ioff of 104~105, and VTH of −4.2 ± 1.3 V. Suchhighly uniform electrical performance on the wafer scale is of highsigniﬁcance in the scalable applications of p-type thin-ﬁlm
semiconductors.

After successfully investigating the intrinsic transport propertiesof TeSeO thin ﬁlms, the operational stability in ambient was also
checked. As shown in Fig. 3g, with 10,000 times on/off switching, theTe0.8Se0.2O0.8 device maintains its output current and good current
modulation ability. Meanwhile, a control experiment was also carriedout on Te0.8Se0.2 samples without oxygen implantation. After 1500
times on/off switching, the Te0.8Se0.2 device loses its transistor performance, possibly because of the electrical/thermal induced phasesegregation21,25. Negative-bias stress (NBS) testing was also investigated on TeSeO thin ﬁlms (Supplementary Fig. 8). After being gated at−20 V for 2 h, the corresponding VTH shifted negatively from −5 to−8.8 V without noticeable subthreshold swing variation under NBS.
Using the equation of σN = CiΔVGS/2e26, the charge-trapping states
density (σN) was calculated to be ~8.2 × 1011 cm−2, indicating the defectstate creation is negligible within the NBS test. In addition, beneﬁting
from the partial oxidation in TeSeO thin ﬁlms that could block theenvironmental inﬂuences, the devices exhibited stable operational

Table 2 | Performance parameters of TeSeO p-channel TFTs
Materials

Ion [μA]

Ion/IoffμFE [cm2/(Vs)]

VTH [V]

Te0.9Se0.1O0.98

72

~102

65.5

25

Te0.8Se0.2O0.8

56

~105

48.5

7.9

Te0.7Se0.3O0.59

18

~104

23.1

5.3

Nature Communications | (2024)15:4440

5

Articlehttps://doi.org/10.1038/s41467-024-48628-zaNanosphere assembling(dry etching)Size reduction(TeSeO deposition)

Nanosphere lift-off

d = 600 nm

d = 100 nm
2 m

c

TeO1.16

10-6

Current (A)Current (A)b@261 nm (UV)
@532 nm (Vis)@1550 nm (IR)

10-6

10

2 m

d

Te0.7Se0.3O0.59

Current (A)

2 m

-7

Te0.5Se0.5O0.32
10-7

10-8

10-9
0

20

40

60

80

100

0

20

Time (s)

10

10-9
10-10
10-11
10

60

80

100

g

-7

-8

Se

10-9
10-10
10-11

10

-12

20

40

60

80

100

-13

10-14

20

Time (s)4060Time (s)

40

60

80

1000

100

@261 nm (UV)
@532 nm (Vis)@1550 nm (IR)

100

10

1

0.1

0

20

Time (s)

10-12

0

0

Responsivity (A/W)

Current (A)

10

-8

f 10

Te0.3Se0.7O0.15

Current (A)e40Time (s)

80

100

9

TeO1.16

2

O 0.3
O 0.1
O 0.5
.7
.5
.3
Se 0
Se 0
Se 0
0.3
0.5
0.7
e
e
e
T
T
T

5

Se

Fig. 4 | Nanopatterned TeSeO and broadband photodetection. a SEM images of
the nanosphere lithography process consisting of nanosphere assembly, size
reduction, TeSeO deposition, and nanosphere lift-off. b–f Broadband UV-vis-SWIR

operation of ﬂexible nanopatterned TeSeO photodetectors with a chopped frequency of 0.2 Hz. g Optical responsivity of TeSeO with different compositions
under various incident light wavelengths.

stability under the long-term storage test (Supplementary Fig. 9). After
300 days of ambient storing, the TeSeO TFT performances show no
discernible degradation in output current, μFE, or hysteresis, even
without device encapsulation. To the best of our knowledge, thesuperior operating/environmental durability of TeSeO is unachievableby other p-type thin-ﬁlm counterparts11.

section)28–30. To achieve a good trade-off between ﬂexibility and conductivity, an inter-aperture wire width of ~100 nm was employed inboth experimental study and theoretical modeling. After that, roomtemperature photodetecting measurements were carried out using
different UV (261 nm), visible (532 nm), and SWIR (1550 nm) lightsources. The Te0.7Se0.3O0.59, Te0.5Se0.5O0.32, and Te0.3Se0.7O0.15 samples show good photoresponse to these tested wavelengths and yieldsigniﬁcant photocurrent under periodic illumination (Fig. 4c–e).
Determined by their optical bandgap and absorption efﬁciency, weak
SWIR response was observed at the Se-rich device (Fig. 4f), while the
TeO1.16 device is highly photosensitive to the SWIR (Fig. 4b). All theperformance parameters of ﬂexible TeSeO photodetectors (PDs) arecalculated and summarized in Fig. 4g. Speciﬁcally, the responsivities of
TeO1.16 and Te0.7Se0.3O0.59 under SWIR irradiation are 603 and225 A/W, respectively, better than the reported intrinsic Te PDs andBroadband photodetection and mechanical robustness of
nanopatterned TeSeO
Semiconducting nanostructures are promising for optoelectronics
because of their high absorption coefﬁcient and superior ﬂexibility10,27.
A maskless nanosphere lithography was employed as a low-cost submicron-scale structure fabrication method to produce honeycomb
TeSeO nanostructures on ﬂexible polyimide (PI) substrates (Fig. 4a andSupplementary Fig. 10, fabrication details shown in Method

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Articlehttps://doi.org/10.1038/s41467-024-48628-zba Strain (%)
4.51

c

3.76
3.01
2.25
1.50
0.75
0.00

Before bending

2000 bending cycles

4000 bending cyclese6000 bending cycles

Response (a.u.)

Current (A)d10-6

rise time = 5 s

decay time = 7 s

10-7
50 s

-40 -20

Time (s)gf6Decay time ( s)

10

105

Hole Mobility (cm2/Vs)

Metal oxides
Perovskite halides
Group III-Vs
Layered materials
Te
TeSeO

104
103
102
101

0

20

40

60

80 100Time ( s)80

Metal oxides
Metal halides
Perovskite halides
Organic materials
CNT
TeSeO

60

40

20

0

0

10

100

101

102

103

104

105

106

Rise time ( s)

0

100

200

300

400

500

600

700

o

Fabrication Temperature ( C)

Fig. 5 | Mechanical analysis of honeycomb TeSeO optoelectronics. a FEA simulation of the TeSeO layer/PI substrate model at a bending radius of 1.5 mm.
b Top views of strain distribution on the bent TeSeO honeycomb layer andc representative area. d The device photocurrent under on/off switching lightillumination (0.2 Hz) as a function of bending cycles. e Time-resolved

photoresponse of Te0.7Se0.3O0.59 PDs measured at 1550 nm illumination with achopped frequency of 10 kHz. Comparison of f photoresponse speed and g holemobility of metal oxides, metal halides, perovskite halides, organic materials,
TeSeO, etc. The corresponding references can be found in Supplementary
Tables 3 and 4.

comparable to those state-of-the-art wideband PDs (Supplementary
Table 4).
Honeycomb structures with nano/micro-scale geometric dimensions can accommodate mechanical deformations and thereby contribute to the superior ﬂexibility of soft (opto-)electronics31–33. Here,the mechanical response of honeycomb TeSeO nanostructure subject
to bending was evaluated by ﬁnite element analysis (FEA, see “Method”
section). Impressively, beneﬁting from the porous structure, the strain
on the TeSeO honeycomb channel located on the substrate center is
efﬁciently dispersed with a bending radius of 1.5 mm (Fig. 5a–c andSupplementary Fig. 11)34. After that, the simulation conditions were
fully reproduced in a real bending experiment to check the mechanicaldurability of nanopatterned TeSeO PDs directly. The whole bending
test with bending times up to 6000 shows no detectable photocurrent

deterioration (Fig. 5d). In contrast, the TeSeO ﬂat ﬁlm without thenanopattern process displayed a signiﬁcant resistance increase withthe bending times (Supplementary Fig. 12), and eventually, the device
broke down because of the appearance of micro-cracks after bending.
Thus, it is indicated that the strain-induced structural damage (e.g.,plastic deformation and crack initiation) and electrical deterioration in
nanopatterned ﬂexible TeSeO could be avoided effectively35.
In addition to the high sensitivity and good mechanical ﬂexibility
demonstrated above, we benchmark our ﬂexible PD performance withthe transient response speed, which highly depends on the efﬁcientcollection/transport of photo-generated carriers16,36,37. The transient
output signals of nanopatterned Te0.7Se0.3O0.59 PDs were measured
under modulated 1550 nm illumination. Even with a chopping frequency up to 10 kHz, the devices exhibit high response reliability

Nature Communications | (2024)15:4440

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Article
without signal distortion (Supplementary Fig. 13). More importantly,
the Te0.7Se0.3O0.59 devices exhibit ultra-fast optical response with therise and decay times being 5 μs and 7 μs (Fig. 5e). The μs-level responsetime is better than most p-channel PDs reported in the literature(Fig. 5f), mainly due to the intrinsic high hole mobility of inorganicblended TeSeO and the high surface-to-volume ratio of honeycomb
structure (Fig. 5g). These observations promise future air-stable andhigh-speed optoelectronic applications based on p-type band-tunable
semiconductors.

Discussion
To summarize, TeSeO, a versatile p-type inorganic semiconductor
system, was designed and deposited as thin ﬁlms and honeycomb
nanostructures at room temperature. By utilizing an inorganic blending strategy, the band structure of TeSeO was engineered to meet the
speciﬁc technical requirements. For instance, by optimizing the TeSeO
formulation, Te0.8Se0.2O0.8 TFTs show high μFE of 48.5 cm2/(Vs) and
Ion/Ioff of ~105, while the ﬂexible honeycomb Te0.7Se0.3O0.59 broadband
PDs show fast optical response down to 5 μs. Importantly, beneﬁting
from the partial oxidation in TeSeO, the devices exhibited good
operational robustness under long-term storage and persistent bias.
These performance parameters surpass those of conventional p-typethin ﬁlms (e.g., metal oxides, metal halides, perovskite halides, andorganic materials) and are on par with the state-of-art n-type scalable
metal oxides (e.g., a-InGaZnO). In this regard, the inorganic-blended
TeSeO system could be applied to diverse functional utilization
beyond the immediate interests in (opto-)electronics.

Methods
Material synthesis
The whole fabrication process of TeSeO ﬁlms was conducted at room
temperature in a scalable manner. First, the SiO2 and polyimide (PI)substrates used in this work were ultrasonically cleaned in acetone,
ethanol, and deionized water and dried by nitrogen gas. Before using,
Te (Sigma–Aldrich, 99.997%, powder) and Se (Sigma–Aldrich, 99.99%,
powder) were mixed and then ground for 30 min. Due to the higher
vapor pressure of Se than Te, less Se powder compared with thedesired Te/Se ratio was added to the mixed source powder. For
instance, to achieve the Te/Se ratios of 7/3, 5/5, and 3/7, the Se powder
with percentages of 17%, 38%, and 55% was added to the mixed source,
respectively. After that, a thermal evaporation process with a deposition rate of 2 Å/s was utilized to deposit TeSe thin ﬁlms with a chamberpressure below 4 × 10−6 Torr at room temperature. The ﬁlm thickness is
proportional to the deposition time, monitored by an INFICON SQC310 deposition controller combined with a quartz crystal oscillator. To
achieve oxygen implantation in TeSeO thin ﬁlms, a standard oxygen
implantation technique (PC-150, JunSun Tech Co., Ltd.) was employedwith a plasma power of 30 W and an O2 gas ﬂow of 50 sccm. The
chamber pressure was set to 0.26 Torr during the oxygen implantation
process with a duration of 60 s.

Material characterization
Surface morphologies of TeSeO ﬁlms were examined with scanningelectron microscopy (SEM, FEI Quanta 450 FEG SEM) and atomic force
microscopy (AFM, Bruker Dimension Icon AFM). A Rigaku SmartLab
X-ray Diffractometer (XRD) with Cu Kα radiation was used to evaluate
the crystallinity and crystal structure of the TeSeO ﬁlms. To get astronger signal from the TeSeO ﬁlm and avoid signal from the substrate, grazing-incidence XRD measurement was performed with aﬁxed grazing-incidence angle of 1°. Crystal structures were also
determined by high-resolution transmission electron microscopy(HRTEM, JEOL 2100F). Elemental mappings were performed using anenergy-dispersive X-ray spectroscopy (EDS) detector attached to aspherical-aberration-corrected scanning transmission electron microscopy (STEM, JEOL JEM-ARM300F2). To realize the elemental andNature Communications | (2024)15:4440

https://doi.org/10.1038/s41467-024-48628-z

chemical analysis of samples, a Thermo Scientiﬁc ESCALAB 250Xi
system was employed to perform ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). Before UPS
and XPS measurement, the samples were cleaned by Ar+ ion etching to
remove surface contamination. All the XPS peaks were calibrated bycarbon (C 1s) peaked at 284.8 eV.

Nanosphere lithography
The monodispersed suspension of polystyrene (PS) nanospheres(10 wt%, in water, diameter of 600 nm) was used in this work. First, PS
nanospheres were self-assembled into close-packed hexagonalarrays at the water-air interface. Then, the close-packed monolayersof PS nanospheres were transferred onto a ﬂexible PI substrate,serving as lithographic masks. After that, a time-dependent dry
oxygen etching process was used to tailor the diameter of PS nanospheres to ~500 nm, which was performed under O2 (50 sccm) at apressure of 0.26 Torr and a radio frequency power of 30 W for 45 s.
After TeSeO ﬁlm deposition, the nanospheres were lifted off by
ultrasonicating the samples in toluene for 60 s, and the TeSeO honeycomb layer with an inter-aperture wire width of ~100 nm wasformed on the PI substrates.

Finite element analysis (FEA)
The mechanical performance of honeycomb TeSeO nanostructures on
ﬂexible PI substrates under bending behavior was simulated and analyzed using FEA with the commercial software ABAQUS. The model
used in this simulation was developed based on real bending experiments and incorporated the actual geometries and loading history.
The PI substrate bent into a semi-circle with a radius of 1.5 mm, causing
the attached honeycomb TeSeO nanostructures to deform accordingly. The slip between the substrate and the TeSeO ﬁlm in the model isneglected. The linear elastic constitutive model was considered in the
FEA simulation, where TeSeO has a Young’s modulus of 31.1 GPa, and PI
has a Young’s modulus of 2.5 GPa, while their Poisson’s ratios are 0.33
and 0.39, respectively. The maximum principle strain distribution of
the TeSeO ﬁlm was obtained in this model.

Device fabrication and characterization
Bottom-gate top-contact thin-ﬁlm transistors were constructed on p+Si/SiO2 substrates, in which the thermally grown oxide thickness is
50 nm. Both channel layers and source/drain electrodes are patterned
through shadow masking to guarantee low gate leakage currents andreliable parameter extraction. The TeSeO channel thickness is ~10 nm
in this work. The 70-nm thick Ni source/drain electrodes were deposited by electron beam evaporation, with a channel width/length of
100 μm/40 μm. Ni electrodes have a high work function of ~5.1 eV,
suitable for contact with p-type semiconductors. Agilent 4155 C semiconductor analyzer was employed to realize electrical characterizations with help from a standard electrical probe station. Field-effectmobility (μFE) in the linear regime can be calculated using μFE = Lgm/
(WCiVDS), where L, W, Ci, and VDS are the channel length, channel width,gate capacitance per unit area, drain-source voltage, respectively. The
gm was transconductance deﬁned as ∂IDS/∂VGS, where IDS is drainsource current and VGS is gate-source voltage. The Ci was calculated
from the parallel plate capacitor model, using Ci = (εA)/d, where thedielectric constant (ε) and ﬁlm thickness (d) of the SiO2 dielectric layer
are 3.9 and 50 nm, respectively. The Ecopia HMS 5300 Hall effectmeasurement system, equipped with a 0.54 T permanent magnet, wasemployed to measure the carrier concentration and Hall mobility using
the van der Pauw method. For the photodetector measurements,
lasers with different wavelengths of ultraviolet (261 nm), visible(532 nm), and short-wave infrared (1550 nm) were used as the lightsources, in which their incident light powers (P) were determined by apower meter (PM400, Thorlabs). To quantify the photodetecting
performance, responsivity (R) was estimated using R = Ip/(PA), where8Article
Ip is photocurrent (deﬁned as light current minus dark current) and A isthe effective irradiated area. The rise and decay times of photodetectors are determined as the time to vary from 10% to 90% of thepeak photocurrent and vice versa.

Data availability
Relevant data supporting the key ﬁndings of this study are available
within the article, the Supplementary Information ﬁle, and the Source
Data ﬁle. All raw data generated during the current study are available
from the corresponding authors. Source data are provided withthis paper.

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Acknowledgements
This work is supported by a fellowship award from the Research Grants
Council of the Hong Kong Special Administrative Region, China(CityURFS2021-1S04) and the Shenzhen Municipality Science and Technology Innovation Commission (grant no. SGDX2020110309300402;“Modulation and Detection of Terahertz Waves based on Semi-Metallic
Two-Dimensional Materials,” CityU). Y.L. and R.F. acknowledge the ﬁnancial support from the Research Grants Council of Hong Kong SAR, China(Grant RFS2021-1S05), NSFC/RGC Joint Research Scheme (Grant
N_HKU159/22) and the Science and Technology Department of Sichuan
Province (Grant 2022YFSY0001).

Author contributions
Y.M. and J.C.H. conceived and initiated the project. Y.M. preparedmaterials, fabricated devices, and performed analysis. R.F., X.C.L., and
Y.L. performed the FEA simulations and microstructure analysis. W.J.W.
and Z.X.L. performed the atomic force microscopy measurement andanalysis. W.J.W. and W.W. contributed to the crystal structure study.
Q.Q., W.J.W., P.S.X., D.C., Z.Y., and C.Y.W. performed part of analysis.
D.J.L., H.S., B.W.L., Z.H.W., and S.P.Y. helped with electrical measurement and analysis. Y.M. and J.C.H. wrote the initial manuscript. All

9

Articlehttps://doi.org/10.1038/s41467-024-48628-z

authors contributed to the ﬁnal manuscript and approved thesubmission.

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The authors declare no competing interests.

Additional information
Supplementary information The online version contains
supplementary material available athttps://doi.org/10.1038/s41467-024-48628-z.
Correspondence and requests for materials should be addressed toChun-Yuen Wong, Yang Lu or Johnny C. Ho.
Peer review information Nature Communications thanks the anonymous reviewers for their contribution to the peer review of this work.
A peer review ﬁle is available.

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