Microwave performance of (Al_0.3Ga_0.7) _0.5in_0.5P, in_0.5Ga_0.5P, Al _0.28Ga_0.72As enhancement-mode pseudomorphic HEMT with succinic acid gate recess process

(Al_0.3Ga_0.7)_0.5In_0.5P, In _0.5Ga_0.5P, Al_0.28Ga_0.72As compounds on GaAs substrates are important materials that are used as Schottky layers in microwave transistors. This study systematically explores the electrical characteristics of various enhancement-mode pseudomorphic high electron mobility transistors (E-mode pHEMTs) with (Al_0.3Ga_0.7) _0.5In_0.5P, In_0.5Ga_0.5P, Al _0.28Ga_0.72As Schottky layers. These E-mode pHEMTs were fabricated using a high-selectivity succinic acid solution for gate recess and buried-Pt gate technology. The (Al_0.3Ga_0.7) _0.5In_0.5P, E-mode pHEMT has a Schottky diode turn-on voltage of 0.76 V. The corresponding values for In_0.5Ga _0.5P, for E-mode pHEMTs are 0.72 and 0.57 V, respectively. Because a larger ΔE_c can be obtained at the (Al_0.3Ga _0.7)_0.5In_0.5P/InGaAs interface, the (Al _0.3Ga_0.7)_0.5In_0.5P E-mode pHEMT also more effectively confined carriers and yielded a higher sheet charge density than other Schottky materials. Based on these measured results, this (Al _0.3Ga_0.7)_0.5In_0.5P E-mode pHEMT is more appropriate for microwave low-noise and high-power device applications.