Search query: Ferroelectric semiconductor heterojunction

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abstract: Ferroelectric Rashba semiconductors (FERSCs) have recently attracted intensive attention due to their giant bulk Rashba parameter, aR, which results in a locking between the spin degrees of freedom and the switchable electric polarization. However, the integration of FERSCs into microelectronic devices has provoked questions concerning whether the Rashba effect can persist when the material thickness is reduced to several nanometers. Here we find that aR can keep a large value of 2.12 eV A in the 5.0 nm thick GeTe film. The behavior of aR with thickness can be expressed by the scaling law and provides a 3D thickness limit of the bulk Rashba effect, dc 2.1 0.5 nm. Finally, we find that the thickness can modify the Berry curvature as well, which influences the polarization and consequently alters the aR. Our results give insight into understanding the factors influencing aR in FERSCs and pave a novel route for designing Rashba type quantum materials.
author_names: Xu Yang

Xiaomei Li

Yang Li

Yan Su Li

Rui Sun

Jia-nan Liu

Xuedong Bai

Na Li

Zong-Kai Xie

Lei Su

Zi-zhao Gong

Xiang-qun Zhang

Wei He

Zhaohua Cheng
title: Three Dimensional Limit of Bulk Rashba Effect in Ferroelectric Semiconductor GeTe.
venue: Nano letters
year: 2020

abstract: We study the optoelectronic properties of a type II heterojunction (HJ) comprising a monolayer of the transition metal dichalcogenide (TMDC) WS2, and a thin film of the organic semiconductor, 3,4,9,10 perylene tetracarboxylic dianhydride (PTCDA) Both theoretical and experimental investigations of the HJ indicate that Frenkel states in the organic layer and two dimensional Wannier Mott states in the TMDC dissociate to form hybrid charge transfer excitons at the interface that subsequently dissociate into free charges that are collected at opposing electrodes. A photodiode employing the HJ achieves a peak external quantum efficiency of 1.8 0.2% at a wavelength of 430 10 nm, corresponding to an internal quantum efficiency (IQE) as high as 11 1% in these ultrathin devices. The photoluminescence spectra of PTCDA and PTCDA/WS2 thin films show that excitons in the WS2 have a quenching rate that is approximately seven times higher than in PTCDA. This difference leads to strong wavelength dependence in IQE.
author_names: Xiao Liu

Jie Gu

Kan Ding

Dejiu Fan

Xiaoer Hu

Yu-wen Tseng

Yi-Hsien Lee

Vinod M Menon

Stephen R Forrest
title: Photoresponse of an Organic Semiconductor/Two Dimensional Transition Metal Dichalcogenide Heterojunction.
venue: Nano letters
year: 2017

abstract: The epitaxial growth of multifunctional oxides on semiconductors has opened a pathway to introduce new functionalities to semiconductor device technologies. In particular, the integration of gate materials that enable nonvolatile or hysteretic functionality in field effect transistors could lead to device technologies that consume less power or allow for novel modalities in computing. Here we present electrical characterization of ultrathin single crystalline SrZrxTi1 xO3 (x 0.7) films epitaxially grown on a high mobility semiconductor, Ge. Epitaxial films of SrZrxTi1 xO3 exhibit relaxor behavior, characterized by a hysteretic polarization that can modulate the surface potential of Ge. We find that gate layers as thin as 5 nm corresponding to an equivalent oxide thickness of just 1.0 nm exhibit a ~2 V hysteretic window in the capacitance voltage characteristics. The development of hysteretic metal oxide semiconductor capacitors with nanoscale gate thicknesses opens new vistas for nanoelectronic devices.
author_names: Reza Maleki Moghadam

Zhiyong Xiao

Kamyar Ahmadi-Majlan

E D Grimley

Mark E Bowden

Phuong-Vu Ong

Scott A Chambers

J M Lebeau

Xia Hong

Peter V Sushko

Joseph H Ngai
title: An Ultrathin Single Crystalline Relaxor Ferroelectric Integrated on a High Mobility Semiconductor.
venue: Nano letters
year: 2017

abstract: Graphene heterostructures in which graphene is combined with semiconductors or other layered 2D materials are of considerable interest, as a new class of electronic devices has been realized. Here we propose a technology platform based on graphene thin film semiconductor metal (GSM) junctions, which can be applied to large scale and power efficient electronics compatible with a variety of substrates. We demonstrate wafer scale integration of vertical field effect transistors (VFETs) based on graphene In Ga Zn O (IGZO) metal asymmetric junctions on a transparent 150 x 150 mm(2) glass. In this system, a triangular energy barrier between the graphene and metal is designed by selecting a metal with a proper work function. We obtain a maximum current on/off ratio (Ion/Ioff) up to 10(6) with an average of 3010 over 2000 devices under ambient conditions. For low power logic applications, an inverter that combines complementary n type (IGZO) and p type (Ge) devices is demonstrated to operate at a bias of only 0.5 V.
author_names: Jinseong Heo

Kyung-Eun Byun

Jaeho Lee

Hyun-Jong Chung

Sanghun Jeon

Seongjun Park

Sungwoo Hwang
title: Graphene and thin film semiconductor heterojunction transistors integrated on wafer scale for low power electronics.
venue: Nano letters
year: 2013

abstract: Low temperature electrostatic force microscopy (EFM) is used to probe unconventional domain walls in the improper ferroelectric semiconductor Er0.99Ca0.01MnO3 down to cryogenic temperatures. The low temperature EFM maps reveal pronounced electric far fields generated by partially uncompensated domain wall bound charges. Positively and negatively charged walls display qualitatively different fields as a function of temperature, which we explain based on different screening mechanisms and the corresponding relaxation time of the mobile carriers. Our results demonstrate domain walls in improper ferroelectrics as a unique example of natural interfaces that are stable against the emergence of electrically uncompensated bound charges. The outstanding robustness of improper ferroelectric domain walls in conjunction with their electronic versatility brings us an important step closer to the development of durable and ultrasmall electronic components for next generation nanotechnology.
author_names: Peggy Schoenherr

Konstantin Shapovalov

Jakob Schaab

Zewu Yan

Edith D Bourret

Mario Hentschel

Massimiliano Stengel

Manfred Fiebig

Andres Cano

Dennis Meier
title: Observation of Uncompensated Bound Charges at Improper Ferroelectric Domain Walls.
venue: Nano letters
year: 2019

abstract: Crystalline oxide ferroelectric tunnel junctions enable persistent encoding of information in electric polarization, featuring nondestructive readout and scalability that can exceed current commercial high speed, nonvolatile ferroelectric memories. However, the well established fabrication of epitaxial devices on oxide substrates is difficult to adapt to silicon substrates for integration into complementary metal oxide semiconductor electronics. In this work, we report ferroelectric tunnel junctions based on 2.8 nm thick BaTiO3 films grown epitaxially on SrTiO3 growth substrates, released, and relaminated onto silicon. The performance of the transferred devices is comparable to devices characterized on the oxide substrate, suggesting a viable route toward next generation nonvolatile memories broadly integrable with different materials platforms.
author_names: Di Lu

S Crossley

Ruijuan Xu

Yasuyuki Hikita

Harold Y Hwang
title: Freestanding Oxide Ferroelectric Tunnel Junction Memories Transferred onto Silicon.
venue: Nano letters
year: 2019

abstract: Enriching the functionality of ferroelectric materials with visible light sensitivity and multiaxial switching capability would open up new opportunities for their applications in advanced information storage with diverse signal manipulation functions. We report experimental observations of robust intralayer ferroelectricity in two dimensional (2D) van der Waals layered a In2Se3 ultrathin flakes at room temperature. Distinct from other 2D and conventional ferroelectrics, In2Se3 exhibits intrinsically intercorrelated out of plane and in plane polarization, where the reversal of the out of plane polarization by a vertical electric field also induces the rotation of the in plane polarization. On the basis of the in plane switchable diode effect and the narrow bandgap ~1.3 eV) of ferroelectric In2Se3, a prototypical nonvolatile memory device, which can be manipulated both by electric field and visible light illumination, is demonstrated for advancing data storage technologies.
author_names: Chaojie Cui

Weijin Hu

Xingxu Yan

Christopher Addiego

Wenpei Gao

Yaoling Wang

Zhe Wang

Linze Li

Yingchun Cheng

Peng Li

Xixiang Zhang

Husam N Alshareef

Tom Wu

Wenguang Zhu

Xiaoqing Pan

Lain-Jong Li
title: Intercorrelated In Plane and Out of Plane Ferroelectricity in Ultrathin Two Dimensional Layered Semiconductor In2Se3.
venue: Nano letters
year: 2018

abstract: For advanced device applications, increasing the compositional abruptness of axial heterostructured and modulation doped nanowires is critical for optimizing performance. For nanowires grown from metal catalysts, the transition region width is dictated by the solute solubility within the catalyst. For example, as a result of the relatively high solubility of Si and Ge in liquid Au for vapor liquid solid (VLS) grown nanowires, the transition region width between an axial Si Ge heterojunction is typically on the order of the nanowire diameter. When the solute solubility in the catalyst is lowered, the heterojunction width can be made sharper. Here we show for the first time the systematic increase in interface sharpness between axial Ge Si heterojunction nanowires grown by the VLS growth method using a Au Ga alloy catalyst. Through in situ tailoring of the catalyst composition using trimethylgallium, the Ge Si heterojunction width is systematically controlled by tuning the semiconductor solubility within a metal Au Ga alloy catalyst. The present approach of alloying to control solute solubilities in the liquid catalyst may be extended to increasing the sharpness of axial dopant profiles, for example, in Si Ge pn heterojunction nanowires which is important for such applications as nanowire tunnel field effect transistors or in Si pn junction nanowires.
author_names: Daniel E Perea

Nan Li

Robert M Dickerson

Amit Misra

Samuel T Picraux
title: Controlling heterojunction abruptness in VLS grown semiconductor nanowires via in situ catalyst alloying.
venue: Nano letters
year: 2011

abstract: Organic semiconductor insulator blend films are widely explored for high performance electronic devices enabled by unique phase separation and self assembly phenomena at key device interfaces. Here we report the first demonstration of high performance hybrid diodes based on p n junctions formed by a p type poly(3 hexylthiophene) (P3HT) poly(methyl methacrylate) (PMMA) blend and n type indium gallium zinc oxide (IGZO) The thin film morphology, microstructure, and vertical phase separation behavior of the P3HT films with varying contents of PMMA are systematically analyzed. Microstructural and charge transport evaluation indicates that the polymer insulator component positively impacts the morphology, molecular orientation, and effective conjugation length of the P3HT films, thereby enhancing the heterojunction performance. Furthermore, the data suggest that PMMA phase segregation creates a continuous nanoscopic interlayer between the P3HT and IGZO layers, playing an important role in enhancing diode performance. Thus, the diode based on an optimal P3HT PMMA blend exhibits a remarkable 10 fold increase in forward current versus that of a neat P3HT diode, yielding an ideality factor value as low as 2.5, and a moderate effective barrier height with an excellent rectification ratio. These results offer a new approach to simplified manufacturing of low cost, large area hybrid inorganic organic electronics technologies.
author_names: Xinan Zhang

Binghao Wang

Wei Huang

G Wang

Weigang Zhu

Zhi Wang

Weifeng Zhang

Antonio F Facchetti

Tobin J Marks
title: Oxide Polymer Heterojunction Diodes with a Nanoscopic Phase Separated Insulating Layer.
venue: Nano letters
year: 2019

abstract: An important factor in the performance of photoelectrochemical water splitting is the band edge alignment of the photoelectrodes for efficient transport and transfer of photogenerated carriers. Many studies for improving charge transfer ability between the electrode and the electrolyte have been reported, while research to improve charge transfer at the interface of the photoactive semiconductor and the conducting substrate is largely lacking. Here, we demonstrate that the water splitting performance of an oxide heterostructured photoelectrode can be increased 6 fold by inserting an atomically thin polar LaAlO3 interlayer compared with that of an oxide heterostructure without an insertion to modify interfacial band offsets. The electrically lowered Schottky barrier is driven by the atomically thin layer, and the charge transfer resistance between the oxides is reduced by up to 2 orders of magnitude upon insertion of LaAlO3, a wide gap (5.6 eV) insulator. We show that the critical thickness of the polar layer for enhancing the charge transfer is 3 unit cells. The dipole moment from the polar sheets of LaAlO3 introduces an internal electric field, which modifies the effective band offsets in the device. This work serves as a proof of concept that photoelectrochemical performance can be improved by manipulating the band offsets of the heterostructure interface, suggesting a new design strategy for heterostructured water splitting photoelectrodes.
author_names: Taemin Kim

Min-Ju Choi

Tae Hyung Lee

Woon Yong Sohn

Ho Won Jang
title: Tailoring of Interfacial Band Offsets by an Atomically Thin Polar Insulating Layer To Enhance the Water Splitting Performance of Oxide Heterojunction Photoanodes.
venue: Nano letters
year: 2019