A GaAs/AlAs Wet Selective Etch Process for the Gate Recess of GaAs Power Metal-Semiconductor Field-Effect Transistors

Abstract

A highly selective wet chemical etch process for gate recess of the GaAs power metal-semiconductor field effect transistors (MES-FETs) was developed. The power MESFETs used in this study were epitaxially grown devices with a 20 Å AlAs etch-stop layer for gate recess. The selective etch process using citric acid/potassium citrate/hydrogen peroxide solution was studied. A selectivity better than 3800:1 was achieved for GaAs/AlAs layers. This selective etch was applied both to high-power, high-voltage power MESFETs and low-voltage large-periphery power MESFETs. For high-power applications, the 14.7 mm device had a breakdown voltage of 22 V. When tested at 1.88 GHz with a drain bias of 10 V, it provided a maximum output power of 38.8 dBm and a maximum power-added efficiency of 52.5%. For low-voltage applications, the 19.8 mm device was tested under IS-95 code-division multiple access (CDMA) modulation at 1.88 GHz with a drain bias of 3.5 V. Under CDMA modulation, the device showed an output power of 28.03 dBm with an adjacent channel power rejection of Ϫ29.6 dBc at 1.25 MHz offset frequency. Both devices also showed excellent uniformity in pinch-off voltages.

Terahertz Electron-Hole Recollisions inGaAs/AlGaAsQuantum Wells: Robustness to Scattering by Optical Phonons and Thermal Fluctuations

“…GaAs, the substrate was removed by a series of etches [19,20]. The final result of the processing was a 1 × 2 mm membrane less than 1 µm thick.…”

“…For the experimental convenience of matching excitonic absorption peaks in the different samples, the band gap of the wider well was raised by adding 5% aluminum to match the 2D band gap of the narrower well. Because HSG is measured in transmission and the exciton absorption lines of the QWs are above the band gap of bulk arXiv:1309.3264v3 [cond-mat.mes-hall] 2 Jan 2014 GaAs, the substrate was removed by a series of etches [19,20]. The final result of the processing was a 1 × 2 mm membrane less than 1 µm thick.…”

AlGaAs/GaAs Quantum Well Infrared Photodetectors

“…The technology of the substrate removal after the assembly of the FPA consisted of the successive processes of the mechanical grinding aimed at removing the main thickness of the GaAs substrate, chemical mechanical polishing and chemical dynamic polishing, in order to obtain a mirror-smooth surface of the array crystal. The processes of the chemical selective etching of the GaAs and heterostructure layers were applied to remove the GaAs substrate from the FPA surface completely (Figure 15) [20][21][22].…”