Search query: Thin-film Schottky barrier photodetector models

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abstract: Phenomenological models for the internal quantum efficiency of Schottky barrier photodetectors suitable for the detection of optical radiation below the bandgap energy of the semiconductor are presented and discussed. The detection mechanism is internal photoemission from the metal film into the semiconductor substrate. Three detector configurations are considered: the first consists of a thick metal film on a semiconductor substrate forming a single Schottky barrier; the second consists of a thin metal film on a semiconductor substrate also forming a single Schottky barrier; and the third consists of a thin metal film buried in semiconductor and forming two Schottky barriers (one along each metal semiconductor interface) In the three cases, illumination through the semiconductor substrate is assumed. The two thin film configurations provide enhanced internal quantum efficiencies due to multiple hot carrier reflections within the metal film, with the double barrier case providing the greatest enhancement due to emission over two barriers. The models proposed are based on assessing the emission probability of hot carriers as a function of their energy, taking into account multiple reflections within the metal film and energy losses due to internal scattering (e.g. with phonons and cold carriers) The thin film single barrier model was tested via comparisons with responsivity measurements reported in the literature for PtSi/p Si and Pd2Si/p Si detectors.
author_names: Christine Scales

Pierre Berini
title: Thin Film Schottky Barrier Photodetector Models
venue: IEEE Journal of Quantum Electronics
year: 2010

abstract: It is generally believed that the resistance degradation behavior of bulk and thin film oxide capacitors arises from the oxygen vacancy migration within the oxide and/or the charge injection at the oxide/electrode interface. The magnitude of the degradation in the resistance has been theoretically studied in the literature by solving the electrochemical transport equations while assuming constant Schottky barrier height. The treatment of constant Schottky barrier height in existing models has led to significant underestimation of the resistance degradation. In this work, I incorporated the dependence of Schottky barrier height on the oxygen vacancy concentration at the interface into the existing model to simulate the degradation process in thin film oxide capacitors. With the consideration of Schottky barrier height lowering from the interface dipole arising from the accumulation of oxygen vacancies at the cathode interface, I found that the leakage current can be increased by more than one order of magnitude, which is more consistent with experimental observations in comparison to the prediction from existing models.
author_names: Feng Xue
title: Effect of Schottky barrier height lowering on resistance degradation of Fe doped SrTiO3 thin film capacitor
year: 2021

abstract: Abstract. A two dimensional model was developed to simulate the optoelectronic characteristics of indium gallium nitride (InxGa1 xN) thin film, Schottky barrier solar cells. The solar cells comprise a window designed to reduce the reflection of incident light, Schottky barrier and ohmic front electrodes, an n doped InxGa1 xN wafer, and a metallic periodically corrugated backreflector. The ratio of indium to gallium in the wafer varies periodically throughout the thickness of absorbing layer of the solar cell. Thus, the resulting InxGa1 xN wafer's optical and electrical properties are made to vary periodically. This material nonhomogeneity could be physically achieved by varying the fractional composition of indium and gallium during deposition. Empirical models for indium nitride and gallium nitride were combined using Vegard's law to determine the optical and electrical constitutive properties of the alloy. The nonhomogeneity of the electrical properties of the InxGa1 xN aids in the separation of the excited electron hole pairs, whereas the periodicities of optical properties and the backreflector enable the incident light to couple to multiple guided wave modes. The profile of the resulting charge carrier generation rate when the solar cell is illuminated by the AM1.5G spectrum was calculated using the rigorous coupled wave approach. The steady state drift diffusion equations were solved using COMSOL, which employs finite volume methods, to calculate the current density as a function of the voltage. Midband Shockley Read Hall, Auger, and radiative recombination rates were taken to be the dominant methods of recombination. The model was used to study the effects of the solar cell geometry and the shape of the periodic material nonhomogeneity on efficiency. The solar cell efficiency was optimized using the differential evolution algorithm.
author_names: Tom H Anderson

Akhlesh Lakhtakia

Peter B Monk
title: Optimization of nonhomogeneous indium gallium nitride Schottky barrier thin film solar cells
year: 2018

abstract: In the present article, we proposed a p n homojunction photodetector with a series Schottky barrier and a high value of responsivity in the ultraviolet region. The thin film photodetector makes use of a junction between an RF sputtered n type ZnO nanostructure and a p type copper doped ZnO (CZO) thin film derived through the spin coating process on an ITO coated glass substrate. Palladium metal contacts have been deposited to form the Schottky barrier in series with the p n homojunction. The device has been simulated, fabricated, and tested only after ensuring the stability of the p type CZO thin film. The measured I V characteristics of the fabricated photodetector under illuminated and dark conditions showed excellent UV response and good rectification properties. The device exhibits a peak responsivity of 13.2 A W 1 for a reverse biasing voltage of 3 V. This value is much higher than the values reported by others for a ZnO based photodetector.
author_names: Lucky Agarwal

Shweta Tripathi
title: High responsivity ZnO based p n homojunction UV photodetector with series Schottky barrier
year: 2020

abstract: The application of Schottky junction in self powered devices is limited by low efficiency in both separation and transport of photogenerated electrons/holes. This issue may be overcome by introducing electronically conductive metal organic framework (EC MOF) materials into the junction and limited by preparing high quality thin films of EC MOFs. In this study, for the first time, high quality EC MOF thin films were demonstrated as effective interlayer materials to solve the above mentioned issue by modulating the height of Schottky barrier (PhB) The EC MOF based self powered Schottky diode can act as a photodetector and demonstrate the highest external quantum efficiency (84% for all reported self powered photodetectors as well as the broadest detectable spectrum range (250 to 1500 nm) high on off ratio ~103) and short rise (0.007 s) and fall time (0.03 s) Furthermore, it can be used as a gas sensor for typical harmful gases and vapors.
author_names: Linan Cao

Ming-Shui Yao

Huijie Jiang

Susumu Kitagawa

Xiaoliang Ye

Wenhua Li

Gang Xu
title: A highly oriented conductive MOF thin film based Schottky diode for self powered light and gas detection
year: 2020

abstract: Abstract A single crystalline ZnGa2O4 epilayer was successfully grown on a c plane (0001) sapphire substrate through metalorganic chemical vapor deposition. A metal semiconductor metal Schottky deep ultraviolet (DUV) photodetector based on a ZnGa2O4 thin film was fabricated through a simple process of E gun evaporation and thermal annealing. At a bias of 10 V, the ZnGa2O4 photodetectors exhibited excellent performance characteristics such as an extremely low dark current (0.86 pA) a responsivity of 0.46 A/W under 230 nm DUV, a high photo/dark current ratio (up to 4.68 x 104) a sharp cutoff wavelength of approximately 270 nm, and short rise and fall times of 0.96 and 0.34 s. The photogenerated holes trapped in the Schottky barrier and the shrinking of the depletion region under DUV illumination enabled high DUV/visible rejection ratio (3 4 orders with a 20 V bias) Therefore, the Fowler Nordheim field tunneling emission functioned as the main electron transport mechanism under DUV illumination and improved the photoelectric characteristics of the epilayer.
author_names: Chiung-yi Huang

Ray-Hua Horng
title: Deep ultraviolet Schottky photodetectors with high deep ultraviolet/visible rejection based on a ZnGa2O4 thin film
year: 2019

abstract: Ferroelectrics are considered next generation photovoltaic (PV) materials. In this work, a switchable and large PV effect is demonstrated in a Pb free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3 0.5(Ba0.7Ca0.3)TiO3 (BZT BCT) thin film fabricated by a pulsed laser deposition technique. The material shows a remarkable PV output of 0.81 V due to its morphotropic phase boundary composition. The observed PV effect is analyzed on the basis of the interfacial Schottky barrier and bulk depolarization field. The poling dependent PV studies revealed that although the Schottky and depolarization field contribute to the PV effect, the latter dominates the PV response beyond the coercive field. Additionally, the importance of this compound in the field of a self biased photodetector is elucidated in terms of calculated photodetector parameters such as responsivity and detectivity. The explored results will bring significant advancement in the field of ferroelectric PV, UV solid state detector applications and also give an additional dimension to the multifunctional ability of the BZT BCT system.Ferroelectrics are considered next generation photovoltaic (PV) materials. In this work, a switchable and large PV effect is demonstrated in a Pb free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3 0.5(Ba0.7Ca0.3)TiO3 (BZT BCT) thin film fabricated by a pulsed laser deposition technique. The material shows a remarkable PV output of 0.81 V due to its morphotropic phase boundary composition. The observed PV effect is analyzed on the basis of the interfacial Schottky barrier and bulk depolarization field. The poling dependent PV studies revealed that although the Schottky and depolarization field contribute to the PV effect, the latter dominates the PV response beyond the coercive field. Additionally, the importance of this compound in the field of a self biased photodetector is elucidated in terms of calculated photodetector parameters such as responsivity and detectivity. The explored results will bring significant advancement in the field of ferroelectric PV, UV solid state detector applications and also give an addit.
author_names: Atal Bihari Swain

Martando Rath

Pranab Parimal Biswas

Mamidanna Sri Ramachandra Rao

Pattukkannu Murugavel
title: Polarization controlled photovoltaic and self powered photodetector characteristics in Pb free ferroelectric thin film
year: 2019

abstract: A two dimensional model was developed to simulate the optoelectronic characteristics of indium gallium nitride (InxGa1 xN) thin film, Schottky barrier junction solar cells. The solar cell comprises a window designed to reduce the reflection of incident light, Schottky barrier and ohmic front electrodes, an n doped InxGa1 xN wafer, and a metallic periodically corrugated back reflector (PCBR) The ratio of indium to gallium in the wafer varies periodically in the thickness direction, and thus the optical and electrical constitutive properties of the alloy also vary periodically. This material nonhomogeneity could be physically achieved by varying the fractional composition of indium and gallium during deposition. Empirical models for indium nitride and gallium nitride, combined with Vegard's law, were used to calculate the optical and electrical constitutive properties of the alloy. The periodic nonhomogeneity aids charge separation and, in conjunction with the PCBR, enables incident light to couple to multiple surface plasmon polariton waves and waveguide modes. The profile of the resulting chargecarrier generation rate when the solar cell is illuminated by the AM1.5G spectrum was calculated using the rigorous coupled wave approach. The steady state drift diffusion equations were solved using COMSOL, which employs finite element methods, to calculate the current density as a function of the voltage. Mid band Shockley Read Hall, Auger, and radiative recombination rates were taken to be the dominant methods of recombination. The model was used to study the effects of the solar cell geometry and the shape of the periodic material nonhomogeneity on efficiency. The solar cell efficiency was optimized using the differential evolution algorithm.
author_names: Tom H Anderson

Akhlesh Lakhtakia

Peter B Monk
title: Optimal indium gallium nitride Schottky barrier thin film solar cells
venue: Optical Engineering Applications
year: 2017

abstract: The switchable ferroelectric photovoltaic (FPV) effect facilitates application of multifunctional photoelectric devices. The drawback of the FPV effect is that it generates a very low photocurrent in highly insulated ferroelectric materials. In contrast, the light induced pyroelectric effect enhances photoelectric performance. Both effects strongly depend on the ferroelectric polarization of the material. In this study, we fabricated and characterized a near ultraviolet photodetector consisting of a Pt/hexagonal TmFeO3/Pt heterojunction. The switchable FPV and light induced pyroelectric effects are both observed in a hexagonal TmFeO3 ferroelectric semiconductor film. An additional potential arises from the light induced pyroelectric effect, which strongly depends on the light intensity. The Schottky barrier height can be modulated by both the poling electric field and light induced pyroelectric potential. Increasing the power density above the threshold leads to switchable polarization via the light induced pyroelectric potential. The coexistence of photovoltaic and pyroelectric effects in the hexagonal TmFeO3 ferroelectric semiconductor makes it possible to develop electronic, thermal, and optical sensors as well as energy conversion devices.The switchable ferroelectric photovoltaic (FPV) effect facilitates application of multifunctional photoelectric devices. The drawback of the FPV effect is that it generates a very low photocurrent in highly insulated ferroelectric materials. In contrast, the light induced pyroelectric effect enhances photoelectric performance. Both effects strongly depend on the ferroelectric polarization of the material. In this study, we fabricated and characterized a near ultraviolet photodetector consisting of a Pt/hexagonal TmFeO3/Pt heterojunction. The switchable FPV and light induced pyroelectric effects are both observed in a hexagonal TmFeO3 ferroelectric semiconductor film. An additional potential arises from the light induced pyroelectric effect, which strongly depends on the light intensity. The Schottky barrier height can be modulated by both the poling electric field and light induced pyroelectric potential. Increasing the power density above the threshold leads to switchable polarization via the light induc.
author_names: Lichuan Jin

Dainan Zhang

Huaiwu Zhang

Miaoqing Wei

Zhiyong Zhong
title: Near ultraviolet photodetector based on hexagonal TmFeO3 ferroelectric semiconductor thin film with photovoltaic and pyroelectric effects
year: 2019

abstract: Abstract. Schottky barrier photodetector (PD) (tungsten/nickel/aluminum nitride) based on stacked tungsten gratings is reported in our work. The absorbance of the grating based structure is obtained using rigorous coupled wave analysis method. In addition, a responsivity value of 6.164 mA W is calculated at l 559.38 nm based on Fowler's model. More than three times enhancement in responsivity is achieved as compared with that of bulk structure (without grating) based Schottky barrier PD. In addition, a detectivity value of 33.11 x 1011 cm Hz1/2 W is obtained. Furthermore, the effect of grating variables and incident angle on responsivity are also demonstrated. In future, the proposed structure can also be used as a plasmonic sensor, absorber, or spectral filter.
author_names: Ankit Kumar Pandey

Anuj Kumar Sharma
title: Schottky barrier photodetector utilizing tungsten grating nanostructure
year: 2020