RF-MBE生长的AlGaN/GaN高电子迁移率晶体管特性

用射频分子束外延技术研制出了室温迁移率为1035cm2/(V·s),二维电子气浓度为1.0×1013cm-2,77K迁移率为2653cm2/(V·s),二维电子气浓度为9.6×1012cm-2的AlGaN/GaN高电子迁移率晶体管材料.用此材料研制的器件(栅长为1μm,栅宽为80μm,源-漏间距为4μm)的室温非本征跨导为186mS/mm,最大漏极饱和电流密度为925mA/mm,特征频率为18.8GHz.     

MOCVD生长的SiC衬底高迁移率GaN沟道层AlGaN/AlN/GaN HEMT结构

用MOCVD技术在高阻6H-SiC衬底上研制出了具有高迁移率GaN沟道层的AlGaN/AlN/GaN高电子迁移率晶体管(HEMT)结构材料,其室温和80K时二维电子气迁移率分别为1944和11588cm2/(V·s),相应二维电子气浓度为1.03×1013cm-2;三晶X射线衍射和原子力显微镜分析表明该材料具有良好的晶体质量和表面形貌,10μm×10μm样品的表面粗糙度为0.27nm.用此材料研制出了栅长为0.8μm,栅宽为1.2mm的HEMT器件,最大漏极饱和电流密度和非本征跨导分别为957mA/mm和267mS/mm.     

Fabrication and characterization of AlGaN/GaN HEMTs with high power gain and efficiency at 8 GHz

State-of-the-art AlGaN/GaN high electron mobility structures were grown on semi-insulating 4H-SiC substrates by MOCVD and X-band microwave power high electron mobility transistors were fabricated and characterized.Hall mobility of 2291.1 cm2/(V·s) and two-dimensional electron gas density of 9.954 × 1012 cm-2 were achieved at 300 K.The HEMT devices with a 0.45-μm gate length exhibited maximum drain current density as high as 1039.6 mA/mm and peak extrinsic transconduct-ance of 229.7 mS/mm.The fT of 30.89 GHz and fmax of 38.71 GHz were measured on the device.Load-pull measurements were performed and analyzed under (-3.5,28) V,(-3.5,34) V and (-3.5,40) V gate/drain direct current bias in class-AB,respectively.The uncooled device showed high linear power gain of 17.04 dB and high power-added efficiency of 50.56％ at 8 GHz when drain biased at (-3.5,28) V.In addition,when drain biased at (-3.5,40) V,the device exhibited a saturation output power dens-ity up to 6.21 W/mm at 8 GHz,with a power gain of 11.94 dB and a power-added efficiency of 39.56％.Furthermore,the low fmax/fT ratio and the variation of the power sweep of the device at 8 GHz with drain bias voltage were analyzed.     

输出功率密度为2.23W/mm的X波段AlGaN/GaN功率HEMT器件

MOCVD技术在蓝宝石衬底上制备出具有高迁移率GaN沟道层的AlGaN/GaN HEMT材料.高迁移率GaN外延层的室温迁移率达741cm2/(V·s),相应背景电子浓度为1.52×1016cm-3;非有意掺杂高阻GaN缓冲层的室温电阻率超过108Ω·cm,相应的方块电阻超过1012Ω/□.50mm HEMT外延片平均方块电阻为440.9Ω/□,方块电阻均匀性优于96％.用此材料研制出了0.2μm栅长的X波段HEMT功率器件,40μm栅宽的器件跨导达到250mS/mm,特征频率fT为77GHz;0.8mm栅宽的器件电流密度达到1.07A/mm,8GHz时连续波输出功率为1.78W,相应功率密度为2.23W/mm,线性功率增益为13.3dB.     

耗尽型选择性掺杂异质结晶体管

设计和研制了耗尽型选择性掺杂异质结晶体管。外延选择性掺杂材料是由本所Fs-Ⅲ型分子束外延炉生长的。制作器件的材料在室温下,霍尔测量的电子迁移率为6500cm2/vs,二维薄层电子浓度ns=91011cm2。在77K时n=75000cm2/vs。测量了具有栅长1.21.5m,栅宽2180m耗尽型异质结器件的直流特性和器件的跨导,室温下gm=110～130ms/mm,而低温77K时,可达到200ms/mm。     

GaAs基单片集成InGaP/AlGaAs/InGaAs增强/耗尽型PHEMTs

提出了一种新结构单片集成增强/耗尽型(E/D)InGaP/AlGaAs/InGaAs赝配高电子迁移率晶体管(PHEMTs).外延层材料通过分子束外延技术生长,在室温下,其电子迁移率和二维电子气浓度分别为5410cm2/(V·s)和1.34×1012cm-2.首次提出了普通光学接触曝光分步制作增强与耗尽型的栅技术方法.研制出了单片集成E/D型PHEMTs,获得良好的直流和交流特性,最大饱和漏电流密度分别为300和340mA/mm,跨导为350和300mS/mm,阈值电压为0.2和-0.4V,增强型的fT和fmax为10.3和12.4GHz,耗尽型的fT和fmax为12.8和14.7GHz.增强/耗尽型PHEMTs的栅漏反向击穿电压都为-14V.     

Characterization and modeling of AlGaN/GaN MOS capacitor with leakage for large signal transistor modeling

Dual mode AlGaN/GaN metal oxide semiconductor (MOS) heterostructure field-effect transistor (HFET) devices were fabricated and characterized. In HFET mode of operation the devices showed an f/sub t//spl middot/L/sub g/ product of 12GHz/spl middot//spl mu/m at Vgs=-2 V. The AlGaN devices showed formation of an accumulation layer under the gate in forward bias and a f/sub t//spl middot/L/sub g/ product of 6GHz/spl middot//spl mu/m was measured at Vgs=5 V. A novel piecewise small signal model for the gate capacitance of MOS HFET devices is presented and procedures to extract the capacitance in presence of gate leakage are outlined. The model accurately fits measured data from 45MHz to 10GHz over the entire bias range of operation of the device.     

Experimental high performance sub-0.1 μm channel nMOSFET's

Very high performance sub-0.1 μm channel nMOSFET's are fabricated with 35 Å gate oxide and shallow source-drain extensions. An 8.8-ps/stage delay at V_dd=1.5 V is recorded from a 0.08 μm channel nMOS ring oscillator at 85 K. The room temperature delay is 11.3 ps/stage. These are the fastest switching speeds reported to date for any silicon devices at these temperatures. Cutoff frequencies (f_T) of a 0.08 μm channel device are 93 GHz at 300 K, and 119 GHz at 85 K, respectively. Record saturation transconductances, 740 mS/mm at 300 K and 1040 mS/mm at 85 K, are obtained from a 0.05 μm channel device. Good subthreshold characteristics are achieved for 0.09 μm channel devices with a source-drain halo process     

新型复合沟道Al0.3Ga0.7N/Al0.05Ga0.95N/GaN HEMT低相位噪声微波单片集成压控振荡器

设计并研制了一种新型复合沟道Al0.3Ga0.7N/Al0.05Ga0.95N/GaN HEMT(CC-HEMT)微波单片集成压控振荡器(VCO),且测试了电路的性能.CC-HEMT的栅长为1μm,栅宽为100μm.叉指金属-半导体-金属(MSM)变容二极管被设计用于调谐VCO频率.为提高螺旋电感的Q值,聚酰亚胺介质被插入在电感金属层与外延在蓝宝石上GaN层之间.当CC-HEMT的直流偏置为Vgs=-3V,Vds=6V,变容二极管的调谐电压从5.5V到8.5V时,VCO的频率变化从7.04GHz到7.29GHz,平均输出功率为10dBm,平均功率附加效率为10.4%.当加在变容二极管上电压为6.7V时,测得的相位噪声为-86.25dBc/Hz(在频偏100KHz时)和-108dB/Hz(在频偏1MHz时),这个结果也是整个调谐范围的平均值.据我们所知,这个相位噪声测试结果是文献报道中基于GaN HEMT单片VCO的最好结果.     

高性能亚100nm栅长氮氧叠层栅介质难熔W/TiN金属栅电极CMOS器件

在国内首次将等效氧化层厚度为1.7nm的N/O叠层栅介质技术与W/TiN金属栅电极技术结合起来,用于栅长为亚100nm的金属栅CMOS器件的制备.为抑制短沟道效应并提高器件驱动能力,采用的关键技术主要包括:1.7nm N/O叠层栅介质,非CMP平坦化技术,T型难熔W/TiN金属叠层栅电极,新型重离子超陡倒掺杂沟道剖面技术以及双侧墙技术.成功地制备了具有良好的短沟道效应抑制能力和驱动能力的栅长为95nm的金属栅CMOS器件.在VDS=±1.5V,VGS=±1.8V下,nMOS和pMOS的饱和驱动电流分别为679和-327μA/μm.nMOS的亚阈值斜率,DIBL因子以及阈值电压分别为84.46mV/dec,34.76mV/V和0.26V.pMOS的亚阈值斜率,DIBL因子以及阈值电压分别为107.4mV/dec,54.46mV/V和0.27V.结果表明,这种结合技术可以完全消除B穿透现象和多晶硅耗尽效应,有效地降低栅隧穿漏电并提高器件可靠性.     

fmax为100GHz的蓝宝石衬底AlGaN/GaN高电子迁移率晶体管

制作了蓝宝石衬底上生长的AlGaN/GaN高电子迁移率晶体管.0V栅压下,0.3μm栅长、100μm栅宽的器件的饱和漏电流密度为0.85A/mm,峰值跨导为225mS/mm;特征频率和最高振荡频率分别为45和100GHz;4GHz频率下输出功率密度和增益分别为1.8W/mm和9.5dB,8GHz频率下输出功率密度和增益分别为1.12W/mm和11.5dB.     

Manufacturing study of yield and performance dependence on gatelength of submicron AlInAs-GaInAs HEMTs

The fabrication, characterization, and statistical analysis of the performance and yield of AlInAs-GaInAs on InP low-noise high electron mobility transistors (HEMTs) with subquarter-micron T-gates fabricated with electron beam lithography are reported. This was undertaken to establish the manufacturability of submicron AlInAs-GaInAs HEMT technology for various low-noise microwave receiver applications. Excellent DC device yield (up to 90%) was obtained from devices to gate widths 300 μm and 1000 μm. A range of minimum noise figures between 0.026 to 0.5 dB at 2 GHz and 0.39 to 0.8 dB at 12 GHz were obtained for 0.15-μm and 0.20-μm gate length devices. The results establish the correlation between the noise figure and yield for this new class of microwave devices     

Design of a low noise distributed amplifier with adjustable gain control in 0.15μm GaAs PHEMT

正A low noise distributed amplifier consisting of 9 gain cells is presented.The chip is fabricated with 0.15-μm GaAs pseudomorphic high electron mobility transistor(PHEMT) technology from Win Semiconductor of Taiwan.A special optional gate bias technique is introduced to allow an adjustable gain control range of 10 dB.A novel cascode structure is adopted to extend the output voltage and bandwidth.The measurement results show that the amplifier gives an average gain of 15 dB with a gain flatness of±1 dB in the 2-20 GHz band.The noise figure is between 2 and 4.1 dB during the band from 2 to 20 GHz.The amplifier also provides 13.8 dBm of output power at a 1 dB gain compression point and 10.5 dBm of input third order intercept point(IIP3),which demonstrates the excellent performance of linearity.The power consumption is 300 mW with a supply of 5 V,and the chip area is 2.36×1.01 mm~2.     

Pseudomorphic AlGaAs/InGaAs/GaAs High Electron Mobility Transistors with Super Low Noise Performances of 0.41 dB at 18 GHz

Fully passivated low noise AlGaAs/InGaAs/GaAs pseudomorphic (PM) HEMT with wide head T-shaped gates were fabricated by dose split electron beam lithography (DSL). The dimensions of gate head and footprint were optimized by controlling the splitted pattern size, dose, and spaces of each pattern. We obtained stable T-shaped gate of 0.15 μm gate length with 1.35 μm-wide head. The maximum extrinsic transconductance was 560 mS/mm. The minimum noise figure measured at 18 GHz at V_ds = 2 V and I_ds = 17 mA was 0.41 dB with associated gain of 8.19 dB. At 12 GHz, the minimum noise figure and an associated gain were 0.26 and 10.25 dB, respectively. These noise figures are the lowest values ever reported for GaAs-based HEMTs. These results are attributed to the extremely low gate resistance of wide head T-shaped gate having a ratio of the head to footprint dimensions larger than 9.     

一种新的T型栅加工技术

研制出的ＰＨＥＭＴ采用一种新的０．１μｍＴ型栅制备方法。将薄膜的纵向可控变为横向可控，应用这一原理，对时间等参量进行控制，获得了０．１～０．３μｍ微细金属栅条，此工艺应用于３ｍｍＰＨＥＭＴ器件研制，器件的直流跨导大于４００ｍＳ／ｍｍ，微波性能在４０ＧＨｚ时，Ｇａｍａｘ达５．６７ｄＢ，特征频率ｆＴ可外推至７４ＧＨｚ，最高振荡频率ｆｍａｘ可达１３０ＧＨｚ。     

A low power high gain UWB LNA in 0.18-μm CMOS

A low power high gain differential UWB low noise amplifier (LNA) operating at 3-5 GHz is presented.A common gate input stage is used for wideband input matching; capacitor cross coupling (CCC) and current reuse techniques are combined to achieve high gain under low power consumption. The prototypes fabricated in 0.18-μm CMOS achieve a peak power gain of 17.5 dB with a -3 dB bandwidth of 2.8-5 GHz, a measured minimum noise figure (NF) of 3.35 dB and -12.6 dBm input-referred compression point at 5 GHz, while drawing 4.4 mA from a 1.8 V supply. The peak power gain is 14 dB under a 4.5 mW power consumption (3 mA from a 1.5 V supply). The proposed differential LNA occupies an area of 1.01 mm~2 including test pads.     

High performance 0.1 μm gate-length p-type SiGe MODFET's andMOS-MODFET's

High performance p-type modulation-doped field-effect transistors (MODFET's) and metal-oxide-semiconductor MODFET (MOS-MODFET) with 0.1 μm gate-length have been fabricated on a high hole mobility SiGe-Si heterojunction grown by ultrahigh vacuum chemical vapor deposition. The MODFET devices exhibited an extrinsic transconductance (g_m) of 142 mS/mm, a unity current gain cut-off frequency (f_T) of 45 GHz and a maximum oscillation frequency (f_MAX) of 81 GHz, 5 nm-thick high quality jet-vapor-deposited (JVD) SiO₂ was utilized as gate dielectric for the MOS-MODFET's. The devices exhibited a lower gate leakage current (1 nA/μm at V_gs=6 V) and a wider gate operating voltage swing in comparison to the MODFET's. However, due to the larger gate-to-channel distance and the existence of a parasitic surface channel, MOS-MODFET's demonstrated a smaller peak g _m of 90 mS/mm, f_T of 38 GHz, and f_max of 64 GHz. The threshold voltage shifted from 0.45 V for MODFET's to 1.33 V for MOS-MODFET's. A minimum noise figure (NF_min) of 1.29 dB and an associated power gain (G_a) of 12.8 dB were measured at 2 GHz for MODFET's, while the MOS-MODFET's exhibited a NF _min of 0.92 dB and a G_a of 12 dB at 2 GHz. These DC, RF, and high frequency noise characteristics make SiGe/Si MODFET's and MOS-MODFET's excellent candidates for wireless communications     

Radiation effect on the optical and electrical properties of CdSe(In)/p-Si heteroj unction photovoltaic solar cells

The efficiency and radiation resistance of solar cells are graded.They are then fabricated in the form of n-CdeSe（In）/p-Si heterojunction cells by electron beam evaporation of a stoichiomteric mixture of CdSe and In to make a thin film on a p-Si single crystal wafer with a thickness of 100μm and a resistivity of～1.5Ω·cm at a temperature of 473 K.The short-circuit current density(j_sc),open-circuit voltage(V_oc),fill factor（ff） and conversion efficiency（η） under 100 mW/cm²（AMI） intensity,are 20 mA/cm²,0.49 V,0.71 and 6%respectively. The cells were exposed to different electron doses（electron beam accelerator of energy 1.5 MeV,and beam intensity 25 mA）.The cell performance parameters are measured and discussed before and after gamma and electron beam irradiation.     

Low-temperature characterization of buried-channel NMOST

A comprehensive characterization of buried-channel NMOS transistors at low temperatures down to 30 K is reported. The mobilities of both surface (accumulation) and bulk (buried-channel) electrons were determined as a function of surface electric field and gate bias voltage, respectively, at low temperatures. Both surface electron mobility and buried-channel electron mobility increase with decreasing temperatures. However, a peak in the buried-channel electron mobility is observed around 80 K if the neutral region extends to regions of high impurity concentrations near the surface. A modified MOSCAP (Poisson solver) was used to obtain spatial distributions of carriers and to predict the C-V curves. Low-frequency noise measurements at low temperatures were carried out at gate voltages corresponding to the accumulation, depletion, and inversion modes of operation of the device. In the accumulation mode, a 1/f dependence is observed similar to surface-channel devices. In the depletion mode, a generation-recombination type of noise is observed with a peak around 150 K. In the inversion mode, noise that is related to the hole inversion layer is observed     

GaAs MESFET's by molecular beam epitaxy

The noise performance of "T" shaped Ti/W/Au gate GaAs Schottky-barrier field-effect transistors fabricated on channel layers grown by molecular-beam epitaxy (MBE) is reported. The nominal gate length was about 0.7 µm with a total gate width of 250 µm. Typical noise figure and the associated gain were 1.2 and 14 dB at 4 GHz, and 1.9 and 8.5 dB at 12 GHz. To out knowledge these are the best results reported to date on devices fabricated using MBE-grown GaAs. These preliminary results show the promise of MBE for high-quality GaAs FET's.