Y.J. Chan

Cryogenic and high temperature operation of Al0.52In0.48P/In0.2Ga0.8As high electron mobility transistors

The cryogenic and high temperature characterization of Al0.52In0.48P/In0.2Ga0.8As high electron mobility transistors (HEMTs) with 1 μm‐long gates, grown by gas‐source molecular‐beam epitaxy is being reported. Bias‐stress measurements at 77 K in the dark showed only 18 mV threshold voltage shift, confirming that trapping effects are negligible in this material system. Successful operation of these HEMTs at temperatures up to 300 °C has been achieved. These results suggest that AlInP/InGaAs HEMTs have potential for cryogenic and high temperature applications.

High power density and power added efficiency of Al/sub 0.5/In/sub 0.5/P/InGaAs doped-channel HFETs

Al/sub 0.5/In/sub 0.5/P/In/sub 0.15/Ga/sub 0.85/As doped-channel HFETs (DCFETs) demonstrate a high breakdown voltage, a high power density, and a high linearity for microwave power device applications due to the improvement of a larger /spl Delta/E/sub c/ (0.45 eV) and a wide bandgap AlInP Schottky layer. The device, biased at V/sub ds/=3.0 V and operated at 2.4 GHz, provided an output power density of 209 mW/mm, a power-added efficiency of 59% and a linear power gain of 17 dB. Two-tone measurement reveals that the 3rd-order inter-modulation at an input power of 0 dBm is -29 dBc and the output intercept point (OIP/sub 3/) is 30.4 dBm for devices with a 1 mm-wide gate.

Fully quaternary In/sub 0.52/(Al/sub 1-x/Ga/sub x/)/sub 0.48/As/In/sub 0.53/(Al/sub x/Ga/sub 1-x/)/sub 0.47/As (x=0.1, 0.2) heterostructures on InP for HFETs

A fully quaternary (FQ-) In/sub 0.52/(Al/sub 1-x/Ga/sub x/)/sub 0.48/As/In/sub 0.53/(Al/sub x/Ga/sub 1-x/)/sub 0.47/As (x=0.1, 0.2) heterostructure was introduced into doped-channel FETs (FQ-DCFETs) on InP substrates. Based on our previous studies, we observed that by adding a small amount of Ga (10%) atoms into the InAlAs Schottky and buffer layers in the HEMT structure, device performance can be enhanced due to a better quality of InAlGaAs material. Furthermore, by adding a small amount of Al (10% or 20%) atoms into the InGaAs channel layers, the associated impact ionization process can be suppressed in this InAlGaAs channel, resulting in an enhancement of breakdown voltage. Therefore, in this report, we combined both techniques to realize the fully quaternary HFETs and characterize their performance.

Reactive ion etching of CHF3+BCl3 for ternary InxAl1−xAs and InxGa1−xAs (x=0.18, 0.3, 0.52) compounds using various In contents

CHF3+BCl3 reactive ion etching etching was used to study the etching of InxGa1−xAs and InxAl1−xAs layers with varied In contents (x=0.18, 0.3, 0.52). By adding CHF3 gas, it is possible to effectively reduce the etching rate of InxAl1−xAs, without any influence on the InxGa1−xAs. The etching rate of InxGa1−xAs decreased with the In content; however, InxAl1−xAs showed the opposite trend. The etching selectivity between the InxGa1−xAs and the InxAl1−xAs layers was increased by reducing the In content.

Selective gate recess RIE etching by CHF/sub 3/+BCl/sub 3/ in InAlAs/InGaAs HEMTs

The selective dry etching between InGaAs and InAlAs is an essential process for gate recess in InP-based HEMT fabrication, which means that the top n/sup +/-InGaAs layer must be etched away, and the etching process is terminated at the underline InAlAs Schottky layer. This etching selectivity between two materials can be realized by the reactive ion-etching, which is not always available from the conventional chemical etching approach. In order to achieve this selectivity, the mixture of CHF/sub 3/ and BCl/sub 3/ gases was proposed in this study to replace the role of CCl/sub 2/F/sub 2/, which has an undesirable impact on the environment. This gas mixture approach has been proven in our previous studies that a high selectivity (/spl sim/30) can be obtained without a significant surface damage in AlGaAs/GaAs heterostructures. The C/sub x/F/sub y/ and non-volatile AlF/sub 3/ products generated in the RIE chamber can prevent the further etching in the Al-contented layers. In this study, we explored this concept to investigate the etching process of InAlAs and InGaAs materials by using CHF/sub 3/+BCl/sub 3/ gas mixture, and apply this approach for gate-recess etching in InP HEMT fabrication.