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Impact of strained silicon on the device performance of a bipolar charge plasma transistor
摘要： In this manuscript we analyze a unique approach to improve the performance of the bipolar charge plasma transistor (BCPT) by introducing a strained Si/SixGe1?x layer as the active device region. For charge plasma realization different metal work-function electrodes are used to induce n+ and p+ regions on undoped strained silicon-on-insulator (sSOI or SixGe1?x) to realize emitter, base, and collector regions of the BCPT. Here, by using a calibrated 2-D TCAD simulation the impact of a Si mole fraction x (in SixGe1?x) on device performance metrics is investigated. The analysis demonstrates the band gap lowering with decreasing Si content or effective strain on the Si layer, and its subsequent advantages. This work reports a significant improvement in current gain, cutoff frequency, and lower collector breakdown voltage (BVCEO) for the proposed structure over the conventional device. The effect of varying temperature on the strained Si layer and its implications on the device performance is also investigated. The analysis demonstrates a fair device-level understanding and exhibits the immense potential of the SixGe1?x material as the device layer. In addition to this, using extensive 2-D mixed-mode TCAD simulation, a considerable improvement in switching transient times are also observed compared to its conventional counterpart.
关键词： bipolar charge plasma transistor (BCPT),mole fraction,cutoff frequency (fT),current gain (β),collector breakdown voltage (BVCEO),strained Si layer,band gap lowering
更新于2025-09-23 15:23:52
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Characteristics of GeSn-based multiple quantum well heterojunction phototransistors: a simulation-based analysis
摘要： Introduction of multiple quantum wells (MQWs) is an efficient way to enhance the light absorption capability in phototransistors. Direct band gap Ge1?xSnx alloy (x?>?0.08) having large absorption coefficient is an attractive material for heterojunction phototransistors (HPTs) compatible with CMOS platform. In this work, simulations are employed to obtain current gain, responsivity and collector current characteristics of Ge/GeSn/Ge HPTs with incorporation of MQWs (Ge0.87Sn0.13/Ge0.83Sn0.17) in the base region. The performances of bulk, single quantum well and MQW HPT structures are examined and compared. Best performance is shown by HPTs having MQW structure over a wide range of base emitter voltage.
关键词： simulation,current gain,heterojunction phototransistors,responsivity,GeSn,multiple quantum wells
更新于2025-09-23 15:21:21
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Ti/Au/Al/Ni/Au low contact resistance and sharp edge acuity for highly scalable AlGaN/GaN HEMTs
摘要： In this letter, we have reported a novel metal scheme Ti/Au/Al/Ni/Au for ohmic contact on AlGaN/GaN high electron mobility transistors (HEMTs). The reported metal scheme is observed to show minimum metal out-diffusion and sharp edge acuity at high temperature annealing, which facilitates aggressive scaling of source drain separation (LSD). We have demonstrated LSD as low as 300 nm with gate length (Lg) of 100 nm for this metal stack. We observed improvement in ON-Resistance (RON) from 3 ?.mm to 1.25 ?.mm, transconductance (gm) from 276 mS/mm to 365 mS/mm, saturation drain current (IDS,sat) from 906 mA/mm to 1230 mA/mm and unity current gain frequency (fT) from 70 GHz to 93 GHz by scaling LSD from 3 μm to 300 nm. The gate length for all devices were 100 nm.
关键词： Edge acuity,HEMT,smooth surface,current gain cut-off frequency,ohmic contact resistance,GaN
更新于2025-09-23 15:21:01
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Effects of Parasitic Region in SiC Bipolar Junction Transistors on Forced Current Gain
摘要： Effects of a parasitic region in SiC BJTs on conductivity modulation and a forced current gain (????) were investigated by using TCAD simulation with various device structures. By introducing an Al+-implanted region below the base parasitic region, ???? can be improved because the implanted region can reduce the base spreading resistance, leading to alleviation of debiasing effect. ???? in devices with various parasitic areas, whose base spreading resistances were reduced by the Al+-implantation, were compared. We found that ???? can be enhanced by expanding the parasitic area if the base spreading resistance is sufficiently reduced. The higher ???? is attributed to an expanded conductivity-modulated region. The collector current spreading in the collector layer and hole injection from the parasitic region as well as from the intrinsic region can play a role to evoke conductivity modulation. Thus, the larger parasitic region can expand the conductivity-modulated region, which results in expansion of an active area and the enhancement of ????, though a higher base voltage is required.
关键词： forced current gain,conductivity modulation,parasitic region,hole injection,SiC BJT,base spreading resistance
更新于2025-09-23 15:21:01
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Comprehensive Analysis and Optimal Design of Ge/GeSn/Ge p-n-p Infrared Heterojunction Phototransistors
摘要： We present a comprehensive analysis of practical p-n-p Ge/Ge1?xSnx/Ge heterojunction phototransistors (HPTs) for design optimization for efficient infrared detection. Our design includes a Ge1?xSnx narrow-bandgap semiconductor as the active layer in the base layer, enabling extension of the photodetection range from near-infrared to mid-infrared to perform wide-range infrared detection. We calculate the current gain, signal-to-noise ratio (SNR), and optical responsivity and investigate their dependences on the structural parameters to optimize the proposed Ge1?xSnx p-n-p HPTs. The results show that the SNR is strongly dependent on the operation frequency and that the introduction of Sn into the base layer can improve the SNR in the high-frequency region. In addition, the current gain strongly depends on the Sn content in the Ge1?xSnx base layer, and a Sn content of 6%–9% maximizes the optical responsivity achievable in the infrared range. These results provide useful guidelines for designing and optimizing practical p-n-p Ge1?xSnx HPTs for high-performance infrared photodetection.
关键词： current gain,sign-to-noise ratio,infrared,heterojunction phototransistors,GeSn alloys
更新于2025-09-09 09:28:46
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Short/mid-wave two-band type II superlattice infrared heterojunction phototransistor
摘要： We report on a short/mid-wave (SW/MW) two-band type II InAs/GaSb superlattice (SL) infrared heterojunction phototransistor (HPT). The structure consists of two back-to-back HPTs for the SW and MW detections. At 77 K, the 50% cut-off wavelength of the SW and MW HPT is 2.6 and 4.2 (cid:22)m, respectively. When the applied bias voltage is 1.2 V, the responsivity is 213 A/W and the current gain is 611 for the SW band while for the MW band, the responsivity is 45.2 A/W and the current gain is 377 at bias voltage of 1.3 V. At 1.2 V, the shot noise limited detectivity D(cid:3) of the SW channel and the MW channel is 1.9(cid:2)1011 and 1.7(cid:2)109 cm(cid:1)Hz0:5/W, respectively.
关键词： two-band detection,Heterojunction phototransistor,current gain,type II InAs/GaSb superlattice
更新于2025-09-09 09:28:46