High-performance submicrometer gatelength GaInAs/InP compositechannel HEMT's with regrown ohmic contacts

This letter reports DC and RF performance of 0.25 μm gatelength GaInAs/InP composite channel HEMT's with nonalloyed, regrown ohmic contacts by MOCVD. Regrown channel contacts are used to achieve low contact resistance (0.35 Ω-mm) to (50 Å) GaInAs/(150 Å) InP composite channel HEMT's. High transconductance (600 mS/mm), high full channel current (650 mA/mm), and high peak cut-off frequencies (F_t=70 GHz, F_max=170 GHz) are observed. Contact transfer resistance of regrown channel contacts is compared to conventional alloyed contacts for varying GaInAs/InP channel composition     

V-band high-efficiency high-power AlInAs/GaInAs/InP HEMT's

The authors report on the state-of-the-art power performance of InP-based HEMTs (high electron mobility transistors) at 59 GHz. Using a 448-μm-wide HEMT with a gate length of 0.15 μm, an output power of 155 mW with a 4.9-dB gain and a power-added efficiency of 30.1% were obtained. By power-combining two of these HEMTs, an output power of 288 mW with 3.6-dB gain and a power-added efficiency of 20.4% were achieved. This is the highest output power reported with such a high efficiency for InP-based HEMTs, and is comparable to the best results reported for AlGaAs/InGaAs on GaAs pseudomorphic HEMTs at this frequency     

Metamorphic AlInAs/GaInAs HEMTs on GaAs Substrates by MOCVD

Metamorphic AlInAs/GaInAs high-electron mobility transistors with very good device performance have been grown by metal-organic chemical vapor deposition (MOCVD), with the introduction of an effective multistage buffering scheme. Measured room-temperature Hall mobilities of the 2-DEG were over 8000 cm²/V ldr s with sheet carrier densities larger than 4 times 10¹² cm^-2. Transistors with 1-mum gate length exhibited transconductance up to 626 mS/mm. The unity current gain cutoff frequency f_T and the maximum oscillation frequency f_max were 39.1 and 71 GHz, respectively. These results are very encouraging toward the manufacturing of metamorphic devices on GaAs substrates by MOCVD.     

High gain AlInAs/GaInAs/InP HEMT's with individually groundedsource finger vias

High gain, millimeter wave AlInAs/GaInAs/InP HEMT's with individually grounded source finger vias have been fabricated for the first time using a high resolution Cl₂:HBr:BCl₃:Ar RIE process. For comparison of device characteristics at millimeter wave frequencies, HEMT's with end source vias were also fabricated on the same wafer. Fixtured RF characterization has revealed significant reduction in source inductance and reverse transmission in addition to higher gain on devices with individual source vias. These superior RF characteristics exhibited by the HEMT with individually grounded source finger vias illustrate the importance of the via technology for high performance InP-based millimeter wave system applications     

High transconductance selfaligned WSi gate AlInAs/GaInAs HIGFETs grown by MOCVD

HIGFETs were fabricated using an AlInAs/GaInAs heterostructure grown by MOCVD. The 1 mu m-gate HIGFET showed a maximum transconductance of 740 mS/mm at room temperature, which is the highest transconductance obtained for HIGFETs. The reduction of the AlInAs layer thickness to 30 nm and the low source resistance are the primary reasons for this enhancement.<>     

基于再生长欧姆接触工艺的220 GHz InAlN/GaN 场效应晶体管

本文在蓝宝石衬底上研制了具有高电流增益截止频率(f_T)的InAlN/GaN异质结场效应晶体管 (HFETs)。基于MOCVD外延n -GaN欧姆接触工艺实现了器件尺寸的缩小,有效源漏间距(L_sd)缩小至600 nm。此外,采用自对准工艺制备了50 nm直栅。由于器件尺寸的缩小,V_gs= 1 V下器件最大饱和电流(I_ds)达到2.11 A/mm,峰值跨导达到609 mS/mm。小信号测试表明,器件f_T达到220 GHz、最大振荡频率(f_max)达到48 GHz。据我们所知,该f_T值是目前国内InAlN/GaN HFETs器件报道的最高结果。     

Gate current in AlInAs/GaInAs heterostructure insulated-gatefield-effect transistors (HIGFETs)

A self-aligned WSi gate heterostructure insulated-gate field-effect transistor (HIGFET) with a gate length of 1 μm was fabricated using an AlInAs/GaInAs heterostructure grown by atmospheric pressure metal-organic chemical vapor deposition (MOCVD). The gate current is investigated experimentally and theoretically. The measured gate current was found to be about two orders of magnitude higher than predicted by theory. The origin of this increase is unclear. However, the theoretical result suggests the possibility of reducing the gate current in AlInAs/GaInAs HIGFETs     

Ohmic contacts on selectively doped AlInAs/GaInAs heterostructures using Ni, AuGe and Au

We studied three different ohmic metals, AuGe-Ni, Ni-AuGe-Au and AuGe-Au, to find the most suitable one for use in selectively doped AlInAs/GaInAs heterostructures. In the past, AuGe-Ni has been the most commonly used metallic structure. However, AuGe-Ni shows a high contact resistance of about 0.2 Ωmm. Using Ni-AuGe-Au, we were able to obtain a low ohmic contact resistance of about 0.1 Ωmm by optimizing the thickness of the Ni layer and the alloying temperature. This resulted, however, in alloyed layers penetrating the semiconductor deeply. More acceptable results were obtained using AuGe-Au, which provided shallow alloyed layers and good surface morphology in addition to a low contact resistance of about 0.1 Ωmm in a wide range of alloying temperatures from 300 to 450°C. Thus we conclude that a simplified structure without Ni is the preferable ohmic metal for selectively doped AlInAs/GaInAs heterostructures.     

Reliability of AlInAs/GaInAs heterojunction bipolar transistors

The reliability of high-performance AlInAs/GaInAs heterojunction bipolar transistors (HBTs) grown by molecular beam epitaxy (MBE) is discussed. Devices with a base Be doping level of 5×10¹⁹ cm^-3 and a base thickness of approximately 50 nm displayed no sign of Be diffusion under applied bias. Excellent stability in DC current gain, device turn-on voltage, and base-emitter junction characteristics was observed. Accelerated life-test experiments were performed under an applied constant collector current density of 7×10⁴ A/cm² at ambient temperatures of 193, 208, and 328°C. Junction temperature and device thermal resistance were determined experimentally. Degradation of the base-collector junction was used as failure criterion to project a mean time to failure in excess of 10⁷ h at 125°C junction temperature with an associated activation energy of 1.92 eV     

Kink-free AlInAs/GaInAs/InP HEMTs grown by molecular beam epitaxy

Kink-free AlInAs/GaInAs/InP HEMTs have been fabricated from an MBE structure grown under normal growth condition. Devices with 1 mu m gate-length exhibit an extrinsic transconductance of 450 mS/mm and a maximum drain current of 600 mA/mm which represent the best results for 1 mu m gate devices. The DC output conductance shows no kink over the entire gate bias range. The elimination of the kink is attributed to the high quality AlInAs buffer layer and a low mismatch between the AlInAs buffer layer and InP substrate.<>     

Double junction AlInAs/GaInAs multiquantum well avalanche photodiodes

A separate absorption, grading, and multiplication avalanche photodiode with an AlInAs/GaInAs multiquantum well multiplication region is reported. This device exhibits a low excess-noise factor and a gain-bandwidth product of 50 GHz, due to the high ratio of ionisation rates of the multiplication material. In addition, a large bandwidth is obtained owing to the use of an undoped (n type) GaInAs absorption layer, fully depleted when multiplication occurs.<>     

AlInAs/GaInAs heterostructure bipolar transistors grown by metalorganic chemical vapour deposition

Al/sub 0.48/In/sub 0.52/As/Ga/sub 0.47/In/sub 0.53/As heterostructure bipolar transistors are demonstrated using metalorganic chemical vapour deposition. The transistors have a cutoff frequency of 80 GHz and a common-emitter breakdown voltage of 5.5 V.<>     

Graded pseudomorphic channel AlInP/AlInAs/GaInAs HEMTs with highchannel breakdown voltage

Reports effects of the composition grading of the channel on the device characteristics of Al_0.48In_0.52As/Ga_1-xIn_xAs pseudomorphic HEMTs. Systematic studies reveal that the modification of the quantum-well channel by grading the composition considerably changes the channel breakdown (BV_ds) and output conductance (G₀ ) characteristics. HEMTs with graded Ga_1-xIn_xAs channel (from x=0.7 to x=0.6) exhibited significantly improved BV_ds (11V) and g₀ (40 mS/mm) compared with HEMTs with uniform composition (x=0.7) in the channel (BV_ds=4V and g₀=80 mS/mm)     

MOCVD-grown AlInAs/GaInAs MODFET with drain currents higher than 1.3 mA/mm

Very high-density and high-mobility AlInAs/GaInAs modulation-doped heterostructures have been successfully grown by low-pressure MOCVD. FETs, having gate-lengths of 0.25 mu m, fabricated from these heterostructures show transconductances as high as 700 mS/mm, and drain saturation currents in excess of 1.3 mA/mm at V/sub gs/=0 V. This current density is among the highest yet reported for FETs grown by any technique. The extracted current-gain cutoff frequency is 78 GHz.<>     

Low-frequency noise characteristics of AlInAs/GaInAs modulation-doped field-effect transistors

The output noise voltage of AlInAs/GaInAs MODFETs grown by both MOCVD and MBE was measured at frequencies from 1 MHz to 1.5 GHz under different bias conditions for the first time. For frequencies below 500 MHz the noise voltage showed a 1/f dependence with a corner frequency around 200 MHz. The low-frequency noise was larger at the bias conditions giving higher transconductance.<>     

50-nm self-aligned-gate pseudomorphic AlInAs/GaInAs high electronmobility transistors

The design and fabrication of a class of 50-nm self-aligned-gate pseudomorphic AlInAs/GaInAs high electron mobility transistors (HEMTs) with potential for ultra-high-frequency and ultra-low-noise applications are reported. These devices exhibit an extrinsic transconductance of 1740 mS/mm and an extrinsic current-gain cutoff frequency of 340 GHz at room temperature. The small-signal characteristics of a pseudomorphic and a lattice-matched AlInAs/GaInAs HEMT with similar gate length (50 nm) and gate-to-channel separation (17.5 nm) are compared. The former demonstrates a 16% higher transconductance and a 15% higher current-gain cutoff frequency, but exhibits a 38% poorer output conductance. An analysis of the high-field transport properties of ultra-short gate-length AlInAs/GaInAs HEMTs shows that a reduction of gate length from 150 to 50 nm neither enhances nor reduces their average velocity. In contrast, the addition of indium from 53% to 80% improves this parameter by 19%     

W/WSi gate self-aligned HIFETs (heterointerface FETs) using anAlInAs/GaInAs heterostructure grown by MOCVD

An undoped AlInAs/GaInAs heterostructure was grown by MOCVD and a W/WSi gate self-aligned HIFET (heterointerface FET) structure was made by ion implantation and rapid thermal annealing. The HIFET, 5 μm in gate length, was of an enhancement-type with a threshold voltage of about 0 V and with a transconductance of 280 mS/mm at room temperature. This result confirms the very high potential of this device for direct coupled FET logic (DCFL)     

A high-speed eight-channel optoelectronic integrated receiver arraycomprising GaInAs p-i-n PD's and AlInAs/GaInAs HEMTs

The successful fabrication of an eight-channel optoelectronic integrated receiver array on an InP substrate, which comprises eighty elements including GaInAs p-i-n photodiodes (PDs) and AlInAs/GaInAs HEMTs, is reported. An average bandwidth of 1.2 GHz with a standard deviation of 190 MHz over the whole channel was obtained. An average responsivity was 546 V/W with a standard deviation of only 19.2 V/W. A crosstalk was less than -30 dB at frequencies between 3 and 900 MHz and as small as -28 dB even at 1 GHz. The yield of chips available for 1.0 Gb/s operation was as high as 62.5% over 2-in-diameter wafer     

GaInAs／AlInAs调制掺杂结构材料的光学性质研究

研究了ＧａＩｎＡｓ／ＡｌＩｎＡｓｎ型调制掺杂结构样品的光致发光及其激发光谱。当空穴态被局域化后．二维电子气的发光线形反映了导带二维态密度的填充效应：导带两个子带填充电子。发光强度则表明，导带第二子带电子波函数在空间上更扩展，与空间分离的空穴产生发光复合的几率较大。激发光谱提供了样品中异质结结构直接带边附近光吸收过程的信息。