基于SiCl4/SF6的GaAs/AlAs ICP选择性干法刻蚀

报道了GaAs/AlAs的电感耦合等离子体(ICP)选择性干法刻蚀,刻蚀气体为SiCl4/SF6混合物.研究了在不同SiCl4/SF6气体配比、RF偏压电源功率和气室压力下,GaAs,AlAs的平均刻蚀速率与二者的选择比.合适的SiCl4/SF6气体比例(15/5sccm),低的RF偏压电源功率和高的气室压力将加强AlF3非挥发性生成物的形成,进而提高GaAs/AlAs的选择比.在SiCl4/SF6气体比例为15/5sccm,RF偏压电源功率为10W,主电源功率为500W,气室压力为2Pa时,GaAs/Al-As的选择比达1500以上.采用喇曼光谱仪对不同RF偏压电源功率和气室压力下,GaAs衬底被刻蚀面等离子体损伤进行了测试,表面形貌和被刻蚀侧壁分别采用原子力显微镜(AFM)和扫描电镜(SEM)进行观察.     

Plasma-Induced Defect-Site Generation in Si Substrate and Its Impact on Performance Degradation in Scaled MOSFETs

Plasma-induced ion-bombardment damage was studied in terms of defect sites created underneath the exposed Si surface. From the shift of capacitance–voltage ($C$– $V$) curves, the defect sites were found to capture carriers (being negatively charged in the case of an Ar plasma exposure). This results in a change of the effective impurity-doping density and the profile. We also report that the defect density depends on the energy of ions from plasma. A simplified and quantitative model is proposed for the drain–current degradation induced by the series-resistance increase by the damage. The relationship derived between the defect density and the drain–current degradation is verified by device simulations. The proposed model is useful to predict the device performance change from plasma process parameters.      

Enhancement mode metamorphicAl0.67In0.33As/Ga0.66In0.34As HEMT on GaAs substrate with high breakdown voltage

This paper presents original and experimental results provided by E-mode Al_0.67In_0.33As/Ga_0.66In_0.34 As metamorphic HEMT. The devices exhibit good dc and rf performances. The 0.4 μm gate length devices have saturation current density of 355 mA/mm at +0.6 V gate-to-source voltage. The Schottky characteristic is a typical reverse gate-to-drain breakdown voltage of -16 V. It is the first time, to our knowledge, that gate current issued from impact ionization have been observed in these devices versus gate to drain extension. These results are the first reported for E-mode Al _0.67In_0.33As/Ga_0.66In_0.34As MM-HEMTs on GaAs substrate     

Novel structure of GaAs-based interdigital-gated HEMT plasma devices for solid-state THz wave amplifier

Theoretical analysis of potential distribution in the interdigital-gated high electron mobility transistor (HEMT) plasma wave device was carried out. The dc I–V characteristics of capacitively coupled interdigital structure showed that uniformity of electric field under the interdigital gates was improved compared to the dc-connected interdigital gate structure. Admittance measurements of capacitively coupled interdigital gate structure in the microwave region of 10–40 GHz showed the conductance modulation by drain–source voltage. These results indicate the existence of plasma wave interactions.     

F等离子体处理 AlGaN/GaN HEMT击穿电压和电流崩塌研究

F等离子体处理工艺被广泛的应用于 AlGaN/GaN HEMT增强型器件的研制和栅前处理工艺。本文研究了低功率F处理 AlGaN/GaN HEMT的击穿特性和电流崩塌特性。随着F处理时间的增加,饱和电流下降,阈值电压正向移动。对不同F处理时间的器件肖特基特性分析后发现,120s的F处理后器件栅泄漏电流明显减小,器件击穿电压提高,当F处理时间大于120s后,由于长时间F处理带来的损伤器件栅泄漏电流没有继续减小。采用不同偏置下的双脉冲测试对不同F处理时间的电流崩塌特性进行了研究,低功率F处理后没有发现明显的电流崩塌现象。     

A Ku-band T-shaped gate GaAs power MESFET with high breakdownvoltage for satellite communications

^GaAs power MESFET's with 0.5-μm T-shaped gate for Ku-band power applications have been developed using a new self-aligned and optical lithography. It displays a maximum current density of 350 mA/mm, an uniform transconductance of 150 mS/mm and a high gate-to-drain breakdown voltage of 35 V. Both the high breakdown voltage and the uniform transconductance were achieved by the new MESFET design incorporating an undoped GaAs cap and a thick lightly doped active layers. The breakdown voltage is the highest one among the values reported on the power devices. The device exhibits 0.61 W/mm power density and 47% power added efficiency with 9.0 dB associated gain at a drain bias of 12 V and an operation frequency of 12 GHz     

Stable tantalum silicide Schottky barrier on n-type gallium arsenide evaluated at elevated temperatures

The high-temperature stability of sputtered tantalum silicide contacts on gallium arsenide has been evaluated. Diodes consisting of Ta silicide on epitaxial n (1.9 × 1017 cm?3; 0.23 ?m/n+ GaAs substrate were annealed at temperatures from 375°C to 800°C. Result show that the ideality factor, barrier height and reverse breakdown voltage remain stable at value of 1.1, 0.79 V and 9 V, respectively. MESFETs with Ta silicide gates exhibited similar drain current/voltage characteristics as conventional Cr/Au gate devices.     

Microwave ZnO Thin-Film Transistors

We have developed ZnO thin-film transistor design and fabrication techniques to demonstrate microwave frequency operation with 2-$muhbox{m}$ gate length devices produced on GaAs substrates. Using $hbox{SiO}_{2}$ gate insulator and pulsed laser deposited ZnO active layers, a drain–current on/off ratio of $hbox{10}^{12}$, a drain–current density of 400 mA/mm, a field-effect mobility of $hbox{110} hbox{cm}^{2}!/ hbox{V}!cdothbox{s}$, and a subthreshold gate voltage swing of 109 mV/dec were achieved. Devices with Ti-gate metal had current and power gain cutoff frequencies of 500 and 400 MHz, respectively.      

Theoretical analysis of the DC avalanche breakdown in GaAs MESFET's

The channel avalanche breakdown in GaAs MESFET's has been investigated using nonstationary electron dynamics and an ionization coefficient taken as a function of average electron energy. Stationary high-field domains of different shapes and peak-field localization are calculated at the breakdown, depending on technological parameters, device geometry or gate bias. Design rules are given to obtain maximum saturated output power and a full-channel current breakdown voltage comparable to the one near pinchoff. In particular, it is found that both a recessed channel geometry and an increased gate-drain distance should yield the best device performances with a doping level not higher than about 1.2-10¹⁷cm^-3and a channel current Idssbetween 275 and 330 mA/mm.     

L波段0.5mm SiC SIT

作为测试小管芯,所研制的小栅宽(0.5 mm)L波段SiC SIT器件,台面和栅凹槽线宽分别为1.0 μm和1.5 μm,源间距2.5 μm,采用凹栅结构、Al注入形成PN结等优化手段,提高了器件的击穿特性和微波特性.0.5 mm栅宽SiC SIT器件,输出功率通过负载牵引系统进行测试,在1.2 GHz CW、50 V...     

GaN HEMT栅工艺优化及性能提升

针对0.5 μm氮化镓高电子迁移率晶体管(GaN HEMT)自对准T型栅工艺,提出一种优化的解决方案。在感应耦合等离子体设备中引入两段法完成氮化硅栅足的干法刻蚀,其中,主刻蚀部分形成具备一定倾斜角度的氮化硅斜面,从而减小栅下沟道电场强度并提高栅金属对氮化硅槽填充的完整性;软着陆部分则以极低的偏置功率对氮化硅进行过刻蚀,确保完全清除氮化硅的同时尽量减小沟道损伤。通过器件优化前后各项特性的测试结果对比发现：优化后的器件关态击穿电压从140 V提升至200 V以上,3.5 GHz下输出功率密度从5.8 W/mm提升至8.7 W/mm,功率附加效率(PAE)从55.5%提升至66.7%。无偏置高加速应力试验96 h后,工艺优化后的器件外观无明显变化,最大电流变化<5%,表明器件可靠性良好。     

On the InGaP/GaAs/InGaAs camel-like FET for high-breakdown,low-leakage, and high-temperature operations

A new field-effect transistor using a high-barrier n⁺ -GaAs/p⁺-InGaP/n-GaAs camel-like gate and GaAs/InGaAs heterostructure-channel has been fabricated successfully and demonstrated. Experimentally, an ultra high gate-drain breakdown voltage of 52 V, a high drain-source operation voltage over 20 V with low leakage currents, and a high drain-source off-state breakdown voltage of 39.7 V are obtained for a 1×100 μm² device. The high breakdown behavior is attributed to the use of high barrier camel-like gate and heterostructure channels to reduce the undesired leakage current. Furthermore, the studied device also shows high breakdown behavior in a high temperature environment and good microwave characteristics. Therefore, based on these characteristics, the studied device is suitable for high-breakdown, low-leakage, and high-temperature applications     

基于MBE生长的一种Be掺杂InGaAs基区的新结构InGaP/InGaAs/GaAs DHBT

报道了一种以InGaAs为基区的新结构InGaP/InGaAs/GaAs双异质结晶体管,获得了直流性能良好的器件.其共射直流增益β达到100,残余电压Voffset约为0.4V,膝点电压Vknee约为1V,击穿电压BVceo超过10V,器件的基极和集电极电流理想因子分别为nb=1.16,nc=1.11,可应用于低功耗、高功率领域.     

High-linearity high-current-drivabilityGa0.51In0.49P/GaAs MISFET usingGa0.51In0.49P airbridge gate structure grown byGSMBE

A novel structure Ga_0.51In_0.49P/GaAs MISFET with an undoped Ga_0.51In_0.49P layer serving as the airbridge between active region and gate pad was first designed and fabricated. Wide and flat characteristics of g_m and f_max versus drain current or gate voltage were achieved. The device also showed a very high maximum current density (610 mA/mm) and a very high gate-to-drain breakdown voltage (25 V). Parasitic capacitances and leakage currents were minimized by the airbridge gate structure and thus high f_T of 22 GHz and high f_max of 40 GHz for 1 μm gate length devices were attained. To our knowledge, both were the best reported values for 1 μm gate GaAs channel FET's     

High breakdown voltage (Al/sub 0.3/Ga/sub 0.7/)/sub 0.5/In/sub 0.5/P/InGaAs quasi-enhancement-mode pHEMT with field-plate technology

A high breakdown voltage and a high turn-on voltage (Al/sub 0.3/Ga/sub 0.7/)/sub 0.5/In/sub 0.5/P/InGaAs quasi-enhancement-mode (E-mode) pseudomorphic HEMT (pHEMTs) with field-plate (FP) process is reported for the first time. Between gate and drain terminal, the transistor has a FP metal of 1 /spl mu/m, which is connected to a source terminal. The fabricated 0.5/spl times/150 /spl mu/m/sup 2/ device can be operated with gate voltage up to 1.6 V owing to its high Schottky turn-on voltage (V/sub ON/=0.85 V), which corresponds to a high drain-to-source current (I/sub ds/) of 420 mA/mm when drain-to-source voltage (V/sub ds/) is 3.5 V. By adopting the FP technology and large barrier height (Al/sub 0.3/Ga/sub 0.7/)/sub 0.5/In/sub 0.5/P layer design, the device achieved a high breakdown voltage of -47 V. The measured maximum transconductance, current gain cutoff frequency and maximum oscillation frequency are 370 mS/mm, 22 GHz , and 85 GHz, respectively. Under 5.2-GHz operation, a 15.2 dBm (220 mW/mm) and a 17.8 dBm (405 mW/mm) saturated output power can be achieved when drain voltage are 3.5 and 20 V. These characteristics demonstrate that the field-plated (Al/sub 0.3/Ga/sub 0.7/)/sub 0.5/In/sub 0.5/P E-mode pHEMTs have great potential for microwave power device applications.     

Inductively coupled plasma etchingof in-based compound semiconductorsin CH4/H2/Ar

Inductively coupled plasma etching of InP, InSb, InGaAs, InGaP and InGaAsP was performed in CH₄/H₂/Ar plasmas as a function of CH₄-to-H₂ ratio ICP source power and rf chuck power. Etch rates as high as 6,000 Å×min⁻¹ were obtained for InP, but the surface is extremely rough (>70 nm root-mean-square roughness) under all conditions due to preferential loss of P. Optical emission spectroscopy shows efficient H₂ dissociation at even moderate ICP source powers, leading to the preferential group V loss. By contrast ternary and quaternary materials show excellent morphologies over a wide range of plasma conditions.     

TiA1和TiPtAu栅GaAs MESFET稳定性研究

在高温和大栅电流下 ,对 Ti Al栅和 Ti Pt Au栅 MESFET的稳定性进行了比较研究 ,结果表明 :( 1)两种器件的击穿电压稳定 ,栅 Schottky接触二极管理想因子 n变化不明显 ;( 2 ) Ti Al栅的 MESFET的栅特性参数 (栅电阻 Rg,势垒高度 Φb)变化明显 ,与沟道特性相关的器件参数 (如最大饱和漏电流 Idss,栅下沟道开路电阻 R0 ,夹断电压 Vp0 等 )保持相对不变 ;( 3)对 Ti Pt Au栅MESFET来说 ,栅 Schottky二极管特性 (栅电阻 Rg,势垒高度 Φb)保持相对稳定 ,与沟道特性相关的器件参数 (如最大饱和漏电流 Idss,栅下沟道开路电阻 R0 ,夹断电压 Vp0 、跨导 gm 等 )明显变化 ,适当退火后 ,有稳定的趋势。这两种器件的参数变化形成了鲜明的对比。     

A 0.15-μm 60-GHz high-power composite channel GaInAs/InP HEMTwith low gate current

This letter presents recent improvements and experimental results provided by GaInAs/InP composite channel high electron mobility transistors (HEMT). The devices exhibit good dc and rf performance. The 0.15-μm gate length devices have saturation current density of 750 mA/mm at V_GS=+0 V. The Schottky characteristic is a typical reverse gate-to-drain breakdown voltage of -8 V. Gate current issued from impact ionization has been studied in these devices, in the first instance, versus drain extension. At 60 GHz, an output power of 385 mW/mm has been obtained in such a device with a 5.3 dB linear gain and 41% drain efficiency which constitutes the state-of-the-art. These results studied are the first reported for a composite channel Al_0.65In_0.35As/Ga_0.47In_0.53 As/InP HEMT on an InP substrate     

用于功率变换的高击穿增强型AlGaN/GaN HEMTs

首次采用CF4等离子体技术实现可用于功率变换的增强性AlGaN/GaN功率器件。实验结果表明,当AlGaN/GaN器件经功率150W和时间150s等离子体轰击后,器件阈值电压从-4V被调制约为0.5V,表现为增强型。当漂移区LGD从5μm增加到15μm,器件的击穿电压从50V迅速增大到400V,电压增幅达350V。采用长度为3μm源场板结构将器件击穿电压明显地提高,击穿电压增加约为475V,且有着比硅基器件更低的比导通电阻,约为2.9mΩ.cm2。器件模拟结果表明,因源场板在远离栅边缘的漂移区中引入另一个电场强度为1.5MV/cm的电场,从而有效地释放了存在栅边缘的电场,将高达3MV/cm的电场减小至1MV/cm。微波测试结果表明,器件的特征频率fT和最大震荡频率fMAX随Vgs改变,正常工作时两参数均在千兆量级。栅宽为1mm的增强型功率管有较好的交直流和瞬态特性,正向电流约为90mA。故增强型AlGaN/GaN器件适合高压高频大功率变换的应用。     

A high power MOSFET with a vertical drain electrode and a meshed gate structure

A MOSFET with a maximum power of 200 W in a 5/spl times/5 mm/SUP 2/ chip which exhibits 20-A current, 3000-millimho transconductance and 100-V breakdown voltage has been developed. The features of the device structure are a vertical drain electrode which makes it possible to use most of the surface area for the source electrode, and a meshed gate structure which realizes an increase in the channel width per unit area. The p-channel device with an offset gate structure was fabricated from an n on p/SUP +/ epitaxial wafer by using polysilicon gate and ion implantation processes. The device can be operated stably at ambient temperatures up to 180/spl deg/C. While the bipolar transistor is a suitable power device in the low voltage region, the MOSFET looks more promising in the high voltage region than the V-FET and the bipolar transistor.