Jun-Chin Huang

Characteristics of In/sub 0.425/Al/sub 0.575/As-InxGa/sub 1-x/As metamorphic HEMTs with pseudomorphic and symmetrically graded channels

In/sub 0.425/Al/sub 0.575/As-In/sub x/Ga/sub 1-x/As metamorphic high electron mobility transistors (MHEMTs) with two different channel designs, grown by molecular beam epitaxy (MBE) system, have been successfully investigated. Comprehensive dc and high-frequency characteristics, including the extrinsic transconductance, current driving capability, device linearity, pinch-off property, gate-voltage swing, breakdown performance, unity-gain cutoff frequency, max. oscillation frequency, output power, and power gain, etc., have been characterized and compared. In addition, complete parametric information of the small-signal device model has also been extracted and discussed for the pseudomorphic channel MHEMT (PC-MHEMT) and the V-shaped symmetrically graded channel MHEMT (SGC-MHEMT), respectively.

Characteristics of δ-doped InAlAs/InGaAs/InP high electron mobility transistors with a linearly graded InxGa1−xAs channel

Various static and microwave performances on InAlAs/InGaAs/InP HEMTs with a linearly-graded InxGa1−xAs channel (LGC-HEMT) have been comprehensively investigated and compared to those having a conventional lattice-matched In0.53Ga0.47As channel (LM-HEMT). Improved carrier transport characteristics and confinement capability by employing the linearly-graded channel have contributed to superior extrinsic transconductance (gm) of 346 mS mm−1, gate-voltage swing (GVS) of 0.5 V (182 mA), unity-gain cut-off frequency (ft) of 41 GHz and maximum oscillation frequency (fmax) of 63 GHz, with an improved frequency operation plateau at 300 K for a gate dimension of 0.65 × 200 µm2. Furthermore, improved kink effects leading to a lower gate leakage current of 0.7 µA mm−1, lower output conductance (gd) of 3.6 mS mm−1, higher voltage gain (AV) of 93.1, higher off-state breakdown voltage of 16.3 V and superior output power characteristics have also been discussed.

Comparative Studies on Double δ -Doped Al0.3Ga0.7As ∕ In x Ga1 − x As ∕ GaAs Symmetrically Graded Doped-Channel Field-Effect Transistors

This work provides comparative studies of a double δ-doped Al 0.3 Ga 0.7 As/In ℵ Ga 1-ℵ As/GaAs symmetrically graded (x = 0.15 → 0.2 → 0.15) doped-channel field-effect transistor (DD-DCFET) with respect to a conventional double 8-doped pseudomorphic high electron mobility transistor (pHEMT) and a conventional DCFET structure. All threes samples, grown by the low-pressure metallorganic chemical vapor deposition (LP-MOCVD) system, have identical layer structures except for their different doping schemes. Comprehensive investigations on the static, microwave, and temperature-dependent characteristics have been made. Possessing the advantages of DCFETs and pHEMTs, the proposed DD-DCFET has demonstrated comprehensively superior linearity, current drive, voltage gain, high-frequency characteristics, and thermal stability characteristics. It is promisingly suitable for millimeter-wave integrated circuit applications.

InAlAs/InGaAs MOS-MHEMTs by Using Ozone Water Oxidation Treatment

This article reports an InAlAs/InGaAs metal oxide semiconductor metamorphic high electron mobility transistor (MOS-MHEMT) by using ozone water oxidation treatment to form an 8.5 nm thick gate oxide with a superior surface flatness. The proposed MHEMT with (without) ozone treatment has demonstrated a lower gate leakage density of 2 μA/mm (0.48 mA/mm) at V gd = -5 V, improved output conductance (g d ) of 8.5 (33.1) mS/mm, gate-voltage swing of 0.9 (0.45) V, enhanced output power of 18.34 (13.43) dBm, and power-added efficiency of 46.8 (26.3)% at 300 K, with gate dimensions of 1 × 200 μm 2 .

A metamorphic heterostructure field-effect transistor with a double delta-doped channel

This study presents a metamorphic heterostructure field-effect transistor with a double δ-doped channel (MDDFET). The coupled δ-doped In0.5Ga0.5As/δ+/In0.5Ga0.5As/In0.6Ga0.4As/In0.5Ga0.5As/δ+/In0.5Ga0.5As channel demonstrates high carrier concentration and high mobility due to the good carrier confinement of the δ-doped design and the coupled wavefunction in the undoped In-rich channel. Experimental results indicate that the MDDFET with the gate dimension of 0.65 × 100 µm2 exhibits a maximum extrinsic transconductance of 320 mS mm−1, a saturated drain current density of 566 mA mm−1 at VGS = 0 V, a cut-off frequency of 45 GHz, a maximum oscillation frequency of 125 GHz and a saturated power of 15.9 dBm at 5.8 GHz. These results demonstrate that this studied device is appropriate for high-frequency and high-power applications.

Improved high-temperature characteristics of a symmetrically graded AlGaAs/InxGa1−xAs/AlGaAs pHEMT

This work investigates the superior high-temperature and high-linearity characteristics of a double δ-doped AlGaAs/InxGa1−xAs/AlGaAs pseudomorphic high electron mobility transistor (pHEMT) with a symmetrically linearly graded InxGa1−xAs channel and a wide energy gap AlGaAs barrier. Distinguished high-temperature device characteristics are presented, including an extrinsic transconductance (gm,max) of 182 (223) mS mm−1, a drain–source saturation current density (IDSS) of 428 (524) mA mm−1, an output conductance of 0.334 (0.352) mS mm−1, a gate-voltage swing (GVS) of 1.45 (1.5) V, a voltage gain (Av) of 505 (658) and a reverse breakdown voltage (BVGD) of −24.1 (−31.2) V at 500 (300) K, respectively, with gate dimensions of 0.65 × 200 µm2. In addition, the device demonstrates a superior stable thermal threshold coefficient (∂Vth/∂T) of −0.55 mV K−1, a thermal GVS coefficient (∂GVS/∂T) of −0.25 mV K−1 and a wide gate-bias range of 1.25 V for a unity-gain cut-off frequency (ft) of over 20 GHz. Consequently, the proposed device shows good potential for high-temperature and high-linearity circuit applications.

Investigations of δ-Doped InAlAs/InGaAs/InP High-Electron-Mobility Transistors with Linearly Graded InxGa1-xAs Channel

Comprehensive investigations of the various static and microwave performances of InAlAs/InGaAs/InP high-electron-mobility transistor (HEMT) with a linearly graded InxGa1-xAs channel (LGC-HEMT) have been conducted. LGC-HEEMT was compared with the same HEMT having a conventional lattice-matched In0.53Ga0.47As channel (LM-HEMT). Improved carrier transport characteristics and confinement capability achieved by employing a linearly graded channel have contributed to a high extrinsic transconductance (gm) of 319 mS/mm, a high unity-gain cutoff frequency ( ft) of 37 GHz, and a maximum oscillation frequency ( fmax) of 51 GHz at 300 K for a gate length of 0.65 µm. The improved gate-voltage swing, turn-on and output power characteristics of LGC-HEMT have also been discussed.

Monolithic AlAs-InGaAs-InGaP-GaAs HRT-FETS with PVCR of 960 at 300 K

This letter reports the significant N-shaped negative-differential resistance characteristics with three-terminal controllability of a monolithic heterostructure resonant tunneling field-effect transistor, realized by integrating the AlAs-In/sub 0.25/Ga/sub 0.75/As-AlAs double-barrier single-well resonant tunneling (RT) structure into the drain regime of the In/sub 0.49/Ga/sub 0.51/P-In/sub 0.25/Ga/sub 0.75/As-GaAs /spl delta/-high-electron mobility transistor. A peak-to-valley current ratio in excess of 960 at room temperature has been demonstrated, with a peak current density (J/sub p/) of 50.6 mA/mm, and a valley current density (J/sub v/) of 52.7 /spl mu/A/mm, respectively, with a transistor gate length of 1.0 /spl mu/m. The maximum current drive density was observed to be 478 A/mm-cm/sup 2/.

High-Power-Density and High-Gain δ -Doped In0.425Al0.575As ∕ In0.425Ga0.575As Low-Voltage for Operation

A -doped In0.425Al0.575As/In0.425Ga0.575As/GaAs metamorphic high electron mobility transistor with an In0.425Ga0.575As channel to effectively relieve the impact-ionization effects has been successfully fabricated by the molecular beam epitaxy system. With the designs of an In0.425Ga0.575As channel layer and a wide-bangap In0.425Al0.575As Schottky-contact layer, good carrier confinement, improved breakdown, low output conductance, and high voltage gain with good linearity have been simultaneously achieved. We have also comprehensively investigated the microwave and power performances as a function of VGS and VDS, respectively. Experimentally, the unity-gain cutoff frequency ft and the maximum oscillation frequency fmax slightly decrease with VDS of above 2 V. However, the power gain and the output power increase as VDS increases from 1 to 5 V. Furthermore, the proposed device has also demonstrated good intermodulation distortion characteristics at lower biases, indicating its promise for the large-scale and low-voltage millimeter-wave integrated circuit applications.

Enhancement of the efficiency of GaAs-based solar cells by sol-gel-synthesized ZnO nanowire arrays as the antireflection layer

nanowire arrays as the antireflection layer Yan-Kuin Su, Chiao-Yang Cheng , Jun-Yen Huang, and Yi-Wen Lee Institute of Microelectronics & Department of Electrical Engineering, National Cheng Kung University, No.1. University Road, Tainan 70101, Taiwan Phone:+886-6-275-7575 ext.62382 *Corresponding author: E-mail:yksu@mail.ncku.edu.tw 2 Advanced Optoelectronic Technology Center, National Cheng Kung University, No.1. University Road, Tainan 70101, Taiwan