跨导为325mS/mm的AlGaN/GaN HFET器件

报道了使用国产GaN外延材料(蓝宝石衬底)的AlGaN/GaN HFET器件的制备以及室温下器件的性能.器件栅采用场板结构,其中栅长为0.3μm,场板长为0.37μm,源漏间距为3μm.器件的饱和电流密度为0.572A/mm,最大漏电流密度为0.921A/mm,最大跨导为325mS/mm,由S参数外推出截止频率和最高振荡频率分别为27.9GHz和33.1GHz.     

0.25μm Gate-Length AlGaN/GaN Power HEMTs on Sapphire with fT of 77GHz

在蓝宝石衬底上用MOCVD技术生长的AlGaN/GaN结构上制作出0.25μm栅长的高电子迁移率功率晶体管. 0.25μm栅长的单指器件测到峰值跨导为250mS/mm，特征频率为77GHz. 功率器件的最大电流密度达到1.07A/mm. 8GHz频率下在片测试80×10μm栅宽器件的输出功率为27.04dBm，同时功率附加效率达到26.5%.     

AlGaN/GaN High Electron Mobility Transistors on Sapphires with fmax of 100GHz

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.     

fT为77GHz的蓝宝石衬底0.25μm栅长AlGaN/GaN高电子迁移率功率器件

在蓝宝石衬底上用MOCVD技术生长的AlGaN/GaN结构上制作出0.25μm栅长的高电子迁移率功率晶体管.0.25μm栅长的单指器件测到峰值跨导为250mS/mm,特征频率为77GHz.功率器件的最大电流密度达到1.07A/mm.8GHz频率下在片测试80×10μm栅宽器件的输出功率为27.04dBm,同时功率附加效率达到26.5%.     

fT为77GHz的蓝宝石衬底0.25μm栅长AlGaN/GaN高电子迁移率功率器件

在蓝宝石衬底上用MOCVD技术生长的AlGaN/GaN结构上制作出0.25μm栅长的高电子迁移率功率晶体管.0.25μm栅长的单指器件测到峰值跨导为250mS/mm,特征频率为77GHz.功率器件的最大电流密度达到1.07A/mm.8GHz频率下在片测试80×10μm栅宽器件的输出功率为27.04dBm,同时功率附加效率达到26.5%.     

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.     

高跨导AlGaN/GaN HEMT器件

报道了生长在蓝宝石衬底上的AlGaN/GaN HEMT器件的制造工艺以及在室温下器件的性能.器件的栅长为1.0μm,源漏间距为4.0μm.器件的最大电流密度达到1000mA/mm,最大跨导高达198mS/mm,转移特性曲线表现出增益带宽较宽的特点.同时由所测得的S参数推出栅长为1.0μm器件的截止频率(fT)和最高振荡频率(fmax)分别为18.7GHz和19.1GHz.     

4 W/mm蓝宝石衬底AlGaN/GaN HEMT

报道了利用南京电子器件研究所生长的蓝宝石衬底AlGaN/GaN异质结材料制作的HEMT,器件功率输出密度达4W/mm。通过材料结构及生长条件的优化,利用MOCVD技术获得了二维电子气(2DEG)面密度为0.97×1013cm-2、迁移率为1000cm2/Vs的AlGaN/GaN异质结构材料,用此材料完成了栅长1μm、栅宽200μm AlGaN/GaN HEMT器件的研制。小信号测试表明器件的fT为17GHz、最高振荡频率fmax为40GHz;负载牵引测试得到2GHz下器件的饱和输出功率密度为4.04W/mm。     

X波段AlGaN/GaN HEMTs Γ栅场板结构研究

基于SiC衬底成功研制X波段0.25 μm栅长带有r栅场板结构的AlGaN/GaN HEMT,设计场板(field plate)长度为0.4 μm,0.6μm,0.7μm,0.9μm.研究了r栅场板长度及不同漏偏压下对器件直流,小信号特性及大信号的影响.器件直流I-V及转移特性并不依赖场板长度变化,增加场板长度器件击穿电压提高可达108 V,器件截止频率及振荡频率下降,输出功率大幅度提高,结合器件小信号提参结果分析.8 GHz下,总栅宽1 mm,场板长度为0.9 μm的器件,连续波输出功率密度7.11 W/mm,功率附加效率(PAE)35.31%,相应线性增益10.25 dB.     

8W AlGaN/GaN HEMT功率器件的研制

报道了基于国产衬底以及国产外延的AlGaN/GaN HEMT X波段功率器件的研究进展.利用国产衬底以及外延材料,优化了器件栅场板的结构,研制成功栅长0.35μm,栅宽为lmm的微波功率器件.该器件输出电流密度达到0.83A/mm,击穿电压大于100V,跨导为236mS/mm,截止频率(fT)达到30GHz,最大振荡频率(fmax)为32GHz,8GHz下在片进行连续波测试,漏端电压为40V时测试得到功率增益4.9dB,输出功率达8W,功率附加效率(PAE)为45%.     

Performance improvement in tensile-strained In/sub 0.5/Al/sub 0.5/As/In/sub x/Ga/sub 1-x/As/In/sub 0.5/Al/sub 0.5/As metamorphic HEMT

This paper proposes a In/sub 0.5/Al/sub 0.5/As/In/sub x/Ga/sub 1-x/As/In/sub 0.5/Al/sub 0.5/As (x=0.3-0.5-0.3) metamorphic high-electron mobility transistor with tensile-strained channel. The tensile-strained channel structure exhibits significant improvements in dc and RF characteristics, including extrinsic transconductance, current driving capability, thermal stability, unity-gain cutoff frequency, maximum oscillation frequency, output power, power gain, and power added efficiency.     

Morphological and electrical characterization of SixCryCzBv thin films

Si_xCr_yC_zB_v thin films with several compositions have been studied for integration of high precision resistors in 0.8 μm BICMOS technology. These resistors, integrated in the back-end of line, have the advantage to provide high level of integration and attractive electrical behavior in temperature, for analog devices. The film morphology and the structure have been investigated through transmission electron microscopy analysis and have been then related to the electrical properties on the base of the percolation theory. According to this theory, and in agreement with experimental results, negative thermal coefficient of resistance (TCR) has been obtained for samples with low Cr content, corresponding to a crystalline volume fraction below the percolation threshold.Samples with higher Cr content exhibit, instead, a variation of the TCR as a function of film thickness: negative TCR values are obtained for thickness lower than 5 nm, corresponding to a crystalline volume fraction below the percolation threshold; positive TCR are obtained for larger thickness, indicating the establishment of a continuous conductive path between the Cr rich grains. This property seems to be determinant in order to assure the possibility to obtain thin film resistors almost independent on the temperature.     

Comparison between Pt/TiO2/Pt and Pt/TaOX/TaOY/Pt based bipolar resistive switching devices

Nonvolatile memories have emerged in recent years and have become a leading candidate towards replacing dynamic and static random-access memory devices. In this article, the performances of TiO₂ and TaO₂ nonvolatile memristive devices were compared and the factors that make TaO₂ memristive devices better than TiO₂ memristive devices were studied. TaO₂ memristive devices have shown better endurance performances (10⁸ times more switching cycles) and faster switching speed (5 times) than TiO₂ memristive devices. Electroforming of TaO₂ memristive devices requires~4.5 times less energy than TiO₂ memristive devices of a similar size. The retention period of TaO₂ memristive devices is expected to exceed 10 years with sufficient experimental evidence. In addition to comparing device performances, this article also explains the differences in physical device structure, switching mechanism, and resistance switching performances of TiO₂ and TaO₂ memristive devices. This article summarizes the reasons that give TaO₂ memristive devices the advantage over TiO₂ memristive devices, in terms of electroformation, switching speed, and endurance.     

The C-V-f and G/ω-V-f characteristics of Al/SiO2/p-Si (MIS) structures

The frequency dependence of capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics of the Al/SiO₂/p-Si metal-insulator-semiconductor (MIS) structures has been investigated taking into account the effect of the series resistance (R_s) and interface states (N_ss) at room temperature. The C-V and G/ω-V measurements have been carried out in the frequency range of 1 kHz to 1 MHz. The frequency dispersion in capacitance and conductance can be interpreted only in terms of interface states and series resistance. The N_ss can follow the ac signal and yield an excess capacitance especially at low frequencies. In low frequencies, the values of measured C and G/ω decrease in depletion and accumulation regions with increasing frequencies due to a continuous density distribution of interface states. The C-V plots exhibit anomalous peaks due to the N_ss and R_s effect. It has been experimentally determined that the peak positions in the C-V plot shift towards lower voltages and the peak value of the capacitance decreases with increasing frequency. The effect of series resistance on the capacitance is found appreciable at higher frequencies due to the interface state capacitance decreasing with increasing frequency. In addition, the high-frequency capacitance (C_m) and conductance (G_m/ω) values measured under both reverse and forward bias were corrected for the effect of series resistance to obtain the real diode capacitance. Experimental results show that the locations of N_ss and R_s have a significant effect on electrical characteristics of MIS structures.     

Very low-noise Al/sub 0.3/Ga/sub 0.7/As/Ga/sub 0.65/In/sub 0.35/As/GaAs single quantum-well pseudomorphic HEMTs

AlGaAs/GaInAs/GaAs pseudomorphic HEMTs with an InAs mole fraction as high as 35% in the channel has been successfully fabricated. The device exhibits a maximum extrinsic transconductance of 700 mS/mm. At 18 GHz, a minimum noise figure of 0.55 dB with 15.0 dB associated gain was measured. At 60 GHz, a minimum noise figure as low as 1.6 dB with 7.6 dB associated gain was also obtained. This is the best noise performance yet reported for GaAs-based HEMTs.<>     

A 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode array

We report a 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode (APD) array. The mean breakdown voltage of the APD was 57.9 V and the standard deviation was less than 0.1 V. The mean dark current was /spl sim/2 and /spl sim/300 nA, and the standard deviation was /spl sim/0.19 and /spl sim/60 nA at unity gain (V/sub bias/ = 13.5 V) and at 90% of the breakdown voltage, respectively. External quantum efficiency was above 40% in the wavelength range from 1.0 to 1.6 /spl mu/m. It was /spl sim/57% and /spl sim/45% at 1.3 and 1.55 /spl mu/m, respectively. A bandwidth of 13 GHz was achieved at low gain.     

Lanthanum diffusion in the TiN/LaOx/HfSiO/SiO2/Si stack

Band edge Complementary Metal Oxide Semiconductor (CMOS) devices are obtained by insertion of a thin LaO_x layer between the high-k (HfSiO) and metal gate (TiN). High temperature post deposition anneal induces Lanthanum diffusion across the HfSiO towards the SiO₂ interfacial layer, as shown by Time of Flight Secondary Ions Mass Spectroscopy (ToF-SIMS) and Atom Probe Tomography (APT). Fourier Transform Infrared Spectroscopy in Attenuated Total Reflexion mode (ATR-FTIR) shows the formation of La-O-Si bonds at the high-k/SiO₂ interface. Soft X-ray Photoelectron Spectroscopy (S-XPS) is performed after partial removal of the TiN gate. Results confirm La diffusion and changes in the La chemical environment.     

Al/sub 0.3/Ga/sub 0.7/As/In/sub x/Ga/sub 1-x/As (0/spl les/x/spl les/0.25) doped-channel field-effect transistors (DCFET's)

The properties of both lattice-matched and strained doped-channel field-effect transistors (DCFET's) have been investigated in AlGaAs/In/sub x/Ga/sub 1-x/As (0/spl les/x/spl les/0.25) heterostructures with various indium mole fractions. Through electrical characterization of grown layers in conjunction with the dc and microwave device characteristics, we observed that the introduction of a 150-/spl Aring/ thick strained In/sub 0.15/Ga/sub 0.85/As channel can enhance device performance, compared to the lattice-matched one. However, a degradation of device performance was observed for larger indium mole fractions, up to x=0.25, which is associated with strain relaxation in this highly strained channel. DCFET's also preserved a more reliable performance after biased-stress testings.<>     

Highly linear Al/sub 0.3/Ga/sub 0.7/N-Al/sub 0.05/Ga/sub 0.95/N-GaN composite-channel HEMTs

We report an Al/sub 0.3/Ga/sub 0.7/N-Al/sub 0.05/Ga/sub 0.95/N-GaN composite-channel HEMT with enhanced linearity. By engineering the channel region, i.e., inserting a 6-nm-thick AlGaN layer with 5% Al composition in the channel region, a composite-channel HEMT was demonstrated. Transconductance and cutoff frequencies of a 1 /spl times/100 /spl mu/m HEMT are kept near their peak values throughout the low- and high-current operating levels, a desirable feature for linear power amplifiers. The composite-channel HEMT exhibits a peak transconductance of 150 mS/mm, a peak current gain cutoff frequency (f/sub T/) of 12 GHz and a peak power gain cutoff frequency (f/sub max/) of 30 GHz. For devices grown on sapphire substrate, maximum power density of 3.38 W/mm, power-added efficiency of 45% are obtained at 2 GHz. The output third-order intercept point (OIP3) is 33.2 dBm from two-tone measurement at 2 GHz.