Silvaco ATLAS Research Articles

Performance Investigation of Dual Trench Split-Control-Gate MOSFET as Hydrogen Gas Sensor: A Catalytic Metal Gate Approach

In this article, Dual Trench Split-Control-Gate MOSFET (DT-SCG-MOSFET) based hydrogen gas sensor considering catalytic palladium metal gate approach is simulated using SILVACO ATLAS TCAD. The inner gate architecture in addition to the outer control gates provides enhanced carrier control. Shift in surface potential, subthreshold current, linear current and threshold voltage are used to investigate the performance of the proposed gas sensor. The contribution of analog metrices like the transconductance and parasitic capacitances are explored thoroughly. Sensitivity as a function of subthreshold current as well as change in threshold voltage for the presence and absence of hydrogen gas molecules have been discussed. Results exhibit the superiority of the proposed gas sensor compared with the reported models in terms of sensitivity and Ion/Ioff ratio and suitable for hydrogen gas detection.

Investigation of Polymer/Si Thin Film Tandem Solar Cell Using TCAD Numerical Simulation.

The current study introduces a two-terminal (2T) thin-film tandem solar cell (TSC) comprised of a polymer-based top sub cell and a thin crystalline silicon (c-Si) bottom sub cell. The photoactive layer of the top sub cell is a blend of PDTBTBz-2F as a polymer donor and PC71BM as a fullerene acceptor. Initially, a calibration of the two sub cells is carried out against experimental studies, providing a power conversion efficiency (PCE) of 9.88% for the top sub cell and 14.26% for the bottom sub cell. Upon incorporating both sub cells in a polymer/Si TSC, the resulting cell shows a PCE of 20.45% and a short circuit current density (Jsc) of 13.40 mA/cm2. Then, we optimize the tandem performance by controlling the valence band offset (VBO) of the polymer top cell. Furthermore, we investigate the impact of varying the top absorber defect density and the thicknesses of both absorber layers in an attempt to obtain the maximum obtainable PCE. After optimizing the tandem cell and at the designed current matching condition, the Jsc and PCE of the tandem cell are improved to 16.43 mA/cm2 and 28.41%, respectively. Based on this TCAD simulation study, a tandem configuration established from an all thin-film model may be feasible for wearable electronics applications. All simulations utilize the Silvaco Atlas package where the cells are subjected to standard one Sun (AM1.5G, 1000 W/m2) spectrum illumination.

Long-wave bilayer graphene/HgCdTe based GBp type-II superlattice unipolar barrier infrared detector

Type-II superlattice (T2SL) material is used to design highly efficient next-generation infrared (IR) detectors. The flexibility of the material allows the integration of unipolar barrier IR detector architecture to suppress generation-recombination currents by blocking the majority charge carriers and improve device performance. This paper presents a self-powered T2SL unipolar barrier detector that operates in the long-wave IR regime. It comprises a contact layer made of p+-bilayer graphene (G) and a barrier layer made of p–-Hg1–xCdx=0.41Te (B) placed over a p+-Hg1–xCdx=0.2217Te absorber layer (p) and is known as the GBp detector. The optoelectronic characterization of the unipolar GBp detector is carried out using the Silvaco Atlas TCAD software. Under self-powered mode operation, the proposed GBp detector exhibits an improvement in photocurrent density of about 108 times. The dark current density of 0.4nA/cm2, the photocurrent responsivity of 7.82 A/W, the quantum efficiency of 91.44%, and the detectivity of 4.48 × 1014 cmHZ1/2/W are found at the liquid nitrogen temperature with a bias of –0.5 V. A dichroic ratio of 249 and a response time of less than 1 ps are likewise exhibited by the GBp detector. The substantial electric field at the contact/barrier heterointerface and the high barrier height in the conduction band, which result in an increased photodetection response, are attributed to this improved performance.

Modeling and simulation assessment of dual material gate Delta(δ) doped fully depleted SOI-FET with effect of interface trap charges

A two–dimensional (2D) analytical model with surface potential changes in the delta doped dual material gate with fully depleted silicon on insulator-MOSFET (DMG-DD-SOIFET) is designed to evaluate device characteristics in consideration of interface trap charges (InTCs). The present paper introduced a novel δ-doped in SOIFET to improve device performance. The potential is modeled via two-dimensional Poisson's equations and interface trap charges (InTCs) impact which is verified with numerical simulations using TCAD tool of Silvaco ATLAS. Further, a parametric investigation is carried out to adjust the dimensions of device for a nano-scaled MOS architecture. The performance investigation model and simulation work also involve the calculation of surface potential, drain current and threshold voltage comprising effects of InTCs. It is found that the proposed DMG-DD-SOIFET suggests excellent immunity for short-channel-effects (SCEs) in addition to better device performance for different InTCs conditions.

Performance Analysis of Top Gate Top Contact TFT Using Different Dielectric Layers

Thin film transistors (TFT) have been gaining special attention from researchers in recent years because they are seen as an alternative to traditional MOSFET for future electronic device development. In this manuscript, the performance characteristics of n-channel Indium-Galium-Zinc-Oxide (IGZO) Top Gate Top Contact (TGTC) Thin Film Transistors (TFTs) for various insulating materials including Al2O3, Ta2O5, HfO2, Si3N4, SiO2, and Y2O3 are investigated and compared. This is followed by a comparison of p-type pentacene-based TGTC Organic Thin Film Transistors (OTFT). During simulation tests, the Silvaco Atlas tool is employed, and the I-V characteristic curve is analyzed to discover the important parameters. The proposed TFT's competency is demonstrated by extensive simulation results that contrast it with other models of a similar nature concerning threshold voltage, current ratio, subthreshold slope, mobility and Figure of Merit (FoM). The results demonstrate a trade-off between mobility and current ratio concerning the permittivity of the dielectric layer, with tantalum oxide (Ta2O5) providing the best outcomes in terms of FoM. According to simulation testing, the tantalum pentoxide (Ta2O5) gate insulating layer based on IGZO surpasses its rivals including the p-channel pentacene-based OTFT by offering mobility of 1.47 cm2V-1s-1, a current ratio of 1.36×106 and FoM of 198.87.

Evaluation of a proposed barium di-silicide tandem solar cell using TCAD numerical simulation

Barium di-silicide (BaSi2) material has attracted noteworthy interest in photovoltaics, thanks to its stability, abundant nature, and excellent production feasibility. In this current work, a two-terminal (2T) monolithic all-BaSi2 tandem solar cell is proposed and explored through extensive TCAD simulation. A BaSi2 bottom sub-cell with a bandgap of 1.3 eV, and a Ba(CxSi1−x)2 top sub-cell with a tunable bandgap are employed in the design. It was found that a bandgap of 1.8 eV, which corresponds to x = 0.78, is the optimum choice to obtain the maximum initial power conversion efficiency (η) of 30%. Then, the tandem performance is optimized by investigating the impact of doping and the thickness of both absorber layers. Further, the current matching point is monitored whilst altering the thickness of the top cell resulting in η = 32.83%%, and a short-circuit current density (Jsc) of 16.47 mA/cm2. Additionally, we have explored the influence of the defect density in the absorbers, and the work function of contacts on the performance parameters. All TCAD simulations are accomplished using the Silvaco Atlas package under AM1.5G illumination.

Ni/Ga2O3 based Schottky diode temperature sensor

Temperature sensors are the integrated part of electronics used in most of the applications. Present work demonstrates the temperature sensor based on ultra-wide bandgap semiconducting material, i.e.,Ga2O3. The material is known for its wider bandgap and radiation hardness properties. Ni/Ga2O3 based Schottky barrier device is simulated for sensing the temperature in the current range of 100 µA to 0.1 µA and in temperature range from 200 K to 600 K using SILVACO Atlas software. Relevant models such as bandgap narrowing, Schokely-Read-Hall, etc. were employed to ensure accuracy in the results. The simulated current–voltage (I-V) plots showed exponential variation and followed ideal thermionic emission model. The I-V plots were used to find the thermal sensitivity of device under considerations, which showed linearity in the measured current range. The maximum sensitivity is estimated as 3.22 mV/K at measuring current level of 0.1 µA.

Modeling, simulation investigation of heterojunction (GaSb/Si) vertical TFET-based dielectric modulated biosensor structure

In this article, an analytical model for dielectric modulated heterojunction (GaSb/Si) vertical tunnel field-feect transistor (DMH-VTFET) based biosensor has been developed and investigated for its biological applications. The presented analytical model incorporates important parameters of biological molecules i.e. dielectric permittivity which provides a generalized view of the physical electrostatics and electrical characteristics of the DMH-VTFET biosensor. Biomolecule immobilization within the cavity causes a change in electrical attributes like surface potential and drain current. It has been analyzed that the various factors (including variations in applied voltages (Vds and Vgs)) results in an impact on the device's electrical characteristics. The results have been validated by comparing the characteristics of the modeling output with simulated outcomes. Furthermore, in this work, the functionality of a label-free biosensor based on a gate overlap DMH-VTFET has also been investigated. The functionality of the DMH-VTFET biosensor is examined with reference to the potential profile, energy band diagram, and drain characteristics for various biomolecules, including Zenin (KC = 7), APTES (KC = 3.57), Gelatin (KC = 12), and Keratin (KC = 10). The substrate layer is divided into eight segments, including source- and drain-depleted segments, to produce the potential model. The pseudo-1-dimensional and 2-dimensional versions of Poisson's equation (PE) are used, respectively, to resolve the potential of each segment. The PEs at the intersegment of various segments are solved using the parabolic approximation process. The Silvaco ATLAS tool is used to recreate the biomolecules using various dielectric constant values for simulation results at technology computer-aided design (TCAD).

Analytical investigation of a triple surrounding gate germanium source metal–oxide–semiconductor field‐effect transistor with step graded channel for biosensing applications

AbstractThis paper proposes a compact analytical model and comprehensively investigates the biosensing performance of a novel dielectric modulated triple surrounding gate germanium source metal–oxide–semiconductor field‐effect transistor with a step graded channel. Solving the 2D Poisson's equation yields an analytical expression of threshold voltage, channel potential, drain current and sub threshold swing. The sensitivity variation in the biosensor has been thoroughly studied by varying different device parameters to investigate its biosensing performance. Graded doping in channel offers enhanced sensitivity than a non‐graded doped channel when the doping of the channel is more near the drain end than source end which is due to stronger electric field and gate capacitance. Effect of fill‐in factor for different biomolecules on the sensitivity has been thoroughly discussed. Different analytical results show an excellent agreement with the simulations done on SILVACO ATLAS TCAD simulator.

Optimization of 14 nm double gate Bi-GFET for lower leakage current

In recent years, breakthroughs in electronics technology have resulted in upgrades in the physical properties of the metal oxide semiconductor field effect transistor (MOSFET) toward smaller sizes and improvements in both quality and performance. Hence, the growth field effect transistor (GFET) is being promoted as one of the worthy contenders due to its superior material characteristics. A 14 nm horizontal double-gate bilayer graphene FET with a high-k/metal gate is proposed, which is composed of hafnium dioxide (HfO 2 ) and tungsten silicide (WSi x ) respectively . It is simulated and modelled using silvaco ATHENA and ATLAS technology computer-aided design (TCAD) tools, as well as the Taguchi L9 orthogonal array (OA). The threshold voltage (V TH ) adjustment implant dose, V TH adjustment implant energy, source/drain (S/D) implant dose, and S/D implant energy have all been investigated as process parameters. While the V TH adjustment tilt angle and the S/D implant tilt angle have both been investigated as noise factors. When compared to the initial findings before optimization, the I OFF has a value of 29.579 nA/µm, indicating a significant improvement. Findings from the optimization technique demonstrate excellent device performance with an I OFF of 28.564 nA/µm, which is closer to the international technology roadmap semiconductor (ITRS) 2013 target than before.

A miniaturized advanced rectenna integrated circuit for implantable applications

This paper presents analysis and design of a new miniaturized advanced rectenna integrated circuit for RF energy harvesting applications. The rectenna circuits consist of (antenna, rectifying circuit) and matching network connected together. The 1 × 4.5 mm2 planar L-shaped dipole antenna implanted inside human ‘s body arm for operation in ISM dual-bands like 1.5GHz and 5.8GHz. The new device quantum well asymmetric spacer tunnel layer (QW-ASPAT) rectifier diodes based on GaAs and InGaAs platforms have been used for the mesa size area of 10 × 10 μm2. The DC, RF, and C-V characteristics of the new rectifier diodes were performed and modelled by using SILVACO ATLAS software. The highest extracted curvature coefficient, kv value of the both QW-ASPAT devices at zero bias was about 33 V−1 compared with the standard structures was 13 V−1. The cut off frequency of the proposed QW-GaAs and QW-InGaAs devices are 26GHz and 46GHz respectively. The fully integrated rectenna circuit was performed by Advanced Design System (ADS) software. The maximum DC output voltage and power of the proposed rectenna system were 0.7 V,1.5 V and 167 μw, 325 μw when used single, and double stage voltage doubler rectifiers respectively at the input RF power of 0 dBm.

A new analytical modelling of 10 nm negative capacitance-double gate TFET with improved cross talk and miller effects in digital circuit applications

In this paper, the workability of a Negative Capacitance (NC)-Double Gate (DG) Tunnel FET (NC-DGTFET) for digital logic circuit implementation has been detailed. New analytical modelling of the drain current of the NC-DGTEFT considering the band to band tunneling (BTBT), Band tail tunneling (BTT) and Source drain tunneling (SDT) have been investigated. Significant IOÑ0.025 μA/μm at 250 mV and SS∼12mv/dec - 22mv/dec with very low IOFF (∼fA/μm) is observed with the optimized device. SILVACO ATLAS and MATLAB have been used to validate the proposed model. The modeled NC-DGTFET based Inverter, NAND/NOR has been implemented and the power, delay propagation, and the power delay product (PDP) of the circuit have been analyzed to show the energy efficacy of the NC-DGTFET in the sub-threshold regime (STR) with respect to baseline TFET (B-TFET). To evaluate the impact of the Miller's effects on the digital performances, NC-DGTFET-based five stages Inverter with Fanout = 1 is considered a device under test (DUT) here. Peak overshoot voltage and delay for different fanout and ferroelectric thickness are detailed to show the efficacy of the proposed logic circuits in sub-threshold regime. Both the cross talk and the Miller effects are mitigated significantly in the NC-DGTFET-based digital circuits.

Investigation of gate-engineered heterostructure tunnel field effect transistor as a label-free biosensor: a compact study.

In this article, the authors have articulated DC as well as transient response of a dielectric modulated gate-engineered heterostructure tunnel field effect transistor (GE-HTFET)-based biosensor for label-free detection. A low (direct) bandgap material, indium arsenide (InAs) has been selectively used in the source region to achieve improved band-to-band tunneling of carriers in the tunnel FET. The extended gate architecture is incorporated to stabilize the biomolecules in the nano-cavity aiding significant boost in ON current sensitivity. Using SILVACO ATLAS TCAD tool, the sensitivity of the biosensor is evaluated considering two important parameters possessed by bio-targets, i.e. dielectric constant (k) and charge density (N). A thorough analysis has been performed to show the impact of variation of dielectric constants and charge density of biomolecules over transfer characteristics of the device. ON current level (Ion) is eventually extracted which is considered here as the suitable sensing parameter of the device. Transient response to detect the settling time of Ion is also demonstrated here in presence of both positively and negatively charged bio-species with varying values of dielectric constant. Then ON current sensitivity is extracted accordingly for different locations of biomolecules within the nano-gap. Finally, an extensive comparative analysis of the present structure in terms of ON current sensitivity is shown to justify its sensing ability as compared to recently reported device structures.

Simulation of High Breakdown Voltage, Improved Current Collapse Suppression, and Enhanced Frequency Response AlGaN/GaN HEMT Using A Double Floating Field Plate

In this paper, DC, transient, and RF performances among AlGaN/GaN HEMTs with a no field plate structure (basic), a conventional gate field plate structure (GFP), and a double floating field plate structure (2FFP) were studied by utilizing SILVACO ATLAS 2D device technology computer-aided design (TCAD). The peak electric fields under the gate in drain-side can be alleviated effectively in 2FFP devices, compared with basic and GFP devices, which promotes the breakdown voltage (BV) and suppresses the current collapse phenomenon. As a result, the ON-resistance increase caused by the current collapse phenomena is dramatically suppressed in 2FFP ~19.9% compared with GFP ~49.8% when a 1 ms duration pre-stress was applied with Vds = 300 V in the OFF-state. Because of the discontinuous FP structure, more electric field peaks appear at the edge of the FFP stacks, which leads to a higher BV of ~454.4 V compared to the GFP ~394.3 V and the basic devices ~57.6 V. Moreover, the 2FFP structure performs lower a parasitic capacitance of Cgs = 1.03 pF and Cgd = 0.13 pF than those of the GFP structure (i.e., Cgs = 1.89 pF and Cgd = 0.18 pF). Lower parasitic capacitances lead to a much higher cut-off frequency (ft) of 46 GHz and a maximum oscillation frequency (fmax) of 130 GHz than those of the GFP structure (i.e., ft = 27 GHz and fmax = 93 GHz). These results illustrate the superiority of the 2FFP structure for RF GaN HEMT and open up enormous opportunities for integrated RF GaN devices.

Breast-Cancer Biomarker (C-erbB-2) Detection in Saliva/Serum Based on In1-xGaxAs/Si Hetero Junction Dopingless TFET Biosensor.

This research article reports the electrical detection of breast-cancer biomarker (C-erbB-2) in saliva/serum based on In1-xGaxAs/Si heterojunction dopingless tunnel FET (HJ-DL-TFET) biosensor for highly sensitive and real-time detection. The work takes into account the interface charge modulation effect in dopingless extended gate heterostructure TFET with embedded nanocavity biosensors for the precise, reliable, and fast detection of antigens present in the body fluids such as saliva in place of blood serum. The reported biosensor is numerically simulated in 2D using the SILVACO ATLAS exhaustive calibrated simulation framework. For the biomolecule immobilization, the proposed biosensor has a dual cavity engraved beneath the dual gate structure. This improves the control of biomolecules over the source-to-channel tunneling rate, as well as the control over the electrical performance parameters of the proposed biosensor. Here, a numerical model for the C-erbB-2 interface charge equivalent is also developed. The analysis of device sensitivity in both saliva and serum environments for various C-erbB-2 concentrations has been carried out. Our study reveals that III-V In1-xGaxAs/Si heterojunction with x composition of 0.2 and extended gate geometry provides an increased tunneling probability, improves the gate control to get a higher ION/IOFF ratio and higher sensitivity. In addition to this, the impact of interface charges corresponding to the different amounts of C-erbB-2 biomarkers on the biosensor sensitivity (in terms of ION/IOFF ratio) yields higher sensitivity of the order of 106.

Ovarian-Cancer Biomarker (HE4) Recognition in Serum Using Hetero TFET Biosensor

Recognition of ovarian-cancer biomarker (HE4) in serum using dual-material In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.53</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.47</sub> As/Si hetero-structure charge-plasma-based extended gate TFET biosensor (DCE-HTFET) has been depicted in this paper. The virtual fabrication flow for the configuration has been mentioned here. Silvaco ATLAS TCAD device simulator is used to optimize the device for better sensitivity. The sensitivity of the proposed model in the serum biosphere for different HE4 concentrations in histological subgroups of ovarian cancer has been investigated. An optimum ON-current to OFF-current sensitivity (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ION/IOFF</sub> ) of 18.2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> and sensitivity regarding sub-threshold swing (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SS</sub> ) of 95% have been achieved for the “Mucinous” type histological sub-group of ovarian-cancer biomarker having 74 pmol/L concentration. The proposed biosensor has been compared with the state-of-the-art literature to highlight its efficacy.

Switch-Beam Antenna Techniques for Bridge Structural Health Monitoring With GaAs-Based Solar Energy Harvesting

<bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">The structural health monitoring (SHM) of bridges with wireless sensor networks (WSNs) is addressed by leveraging two distinct but interrelated aspects: GaAs-based solar energy harvesting and switched-beam antenna strategies in combination with asynchronous media access control (MAC) protocols. The joint optimization of solar energy harvesting and switched-beam directional antennas at the nodes is considered and compared with an equivalent omnidirectional antenna network. To address the limited energy budget in battery-based sensor nodes which is a serious limitation in long-lived applications such as bridge SHM, an efficient solar harvesting solution is put forth based on the good performance of GaAs cells even under low-light conditions. Given the current state of the art in GaAs cells, single-junction cells were selected due to the cost of double-or triple-junction versions. The simulation model includes the residual energy capacity with GaAs-based solar energy harvesting of actual selected components (microcontroller, radio interface chip). The model was implemented on top of the Omnet<inline-formula> <tex-math notation="LaTeX">$++$</tex-math> </inline-formula> and Silvaco Atlas simulator. The comparative study in this article provides insights into realistic bridge SHM sensor networks, leveraging solar energy harvesting and switched-beam antennas.</b>

Qualitative Analysis of DG-TFET Structures with Gate Material Engineering

The paper largely focuses on enhancing device parameters of a Double Gate Tunnel Field Effect Transistor structure such as ON current, OFF Current,transconductance and ratio of ON current to OFF current (ION / IOFF) using hetero dielectric gate material. The paper presents three state of art of dual gate TFET i.e., Conventional Double Gate TFET (CDGTFET), horizontally placed Dual Material Double Gate TFET (HDMDGTFET), vertically placed Dual Material Double Gate TFET (VDMDGTFET). The dual material dielectric combinations used in the structures are (SiO2-TiO2), (HfO2-TiO2) and (SiO2-SiC). The Structures are being modeled using Silvaco Atlas tool. Simulations of these structures are carried out and various electrical parameters have been obtained. The results obtained from simulation of these structures are being presented and discussed in this paper. Comparison of the three structures is carried out and resulted in the reduction of ON Current and OFF Current is observed.

Design and Analysis of Charge Plasma-Based Vertical-Nanowire Tunnel FET for Biosensor

In the semiconductor industry, nanoscale devices have better ability to provide for biomolecules detection, but they face various problems during fabrication process, such as high doping concentration, random dopant fluctuation (RDF), higher production cost, low electrostatic control. To overcome these problems, charge plasma (CP) technique has been introduced by the formation of hafnium material at drain side and platinum material at source side with appropriate work-function. The proposed work charge plasma-based vertical-nanowire tunnel FET (CP-VNWTFET) has been designed and analyzed for biosensor application using different dielectric constant and gate underlap method by creating a cavity area under the gate metal. The sensitivity ([Formula: see text]) of biosensor is calculated in terms of change in drain-current ([Formula: see text]) and transconductance ([Formula: see text]) by immobilizing the biomolecules such as Urease, Keratin, Streptavidin, ChOX, Zein, Gluten using gate underlap and dielectric modulation technique. The performance parameters like subthreshold slope (SS), off-current ([Formula: see text]), on-current ([Formula: see text]), on/off current ratio ([Formula: see text]) of the CP-VNWTFET have also been observed while varying the neutral and charged biomolecules at various biased conditions. The device is simulated by using Silvaco ATLAS simulator. The proposed device has been found to be suitable for low power sensor design application.

Simulation Study on the Structure Design of p-GaN/AlGaN/GaN HEMT-Based Ultraviolet Phototransistors.

This work investigates the impacts of structural parameters on the performances of p-GaN/AlGaN/GaN HEMT-based ultraviolet (UV) phototransistors (PTs) using Silvaco Atlas. The simulation results show that a larger Al content or greater thickness for the AlGaN barrier layer can induce a higher two-dimensional electron gas (2DEG) density and produce a larger photocurrent. However, they may also lead to a larger dark current due to the incomplete depletion of the GaN channel layer. The depletion conditions with various Al contents and thicknesses of the AlGaN layer are investigated in detail, and a borderline between full depletion and incomplete depletion was drawn. An optimized structure with an Al content of 0.23 and a thickness of 14 nm is achieved for UV-PT, which exhibits a high photocurrent density of 92.11 mA/mm, a low dark current density of 7.68 × 10-10 mA/mm, and a large photo-to-dark-current ratio of over 1011 at a drain voltage of 5 V. In addition, the effects of other structural parameters, such as the thickness and hole concentration of the p-GaN layer as well as the thickness of the GaN channel layer, on the performances of the UV-PTs are also studied in this work.