Reduction of gap states of ternary III–V semiconductor surfaces by sulfur passivation: Comparative studies of AlGaAs and InGaP

Abstract

Articles you may be interested inTwodimensional bulk bands and surface resonances originated from (100) surfaces of III-V semiconductor compounds AIP Conf.The effects of sulfur passivation on liquid-phase-epitaxy-grown n-type InGaP and AlGaAs surfaces have been studied using x-ray photoelectron spectroscopy. The surfaces were simultaneously prepared through degreasing and the use of an aqueous ͑NH 4 ͒ 2 S x treatment in air. For InGaP, sulfur atoms initially reacted with both surface In and Ga atoms and reacted negligibly with P atoms. The band bending was reduced by 0.7 eV compared to a sputter-cleaned surface. Presumably, sulfur eliminated P-vacancy-related gap states by occupying P sites and forming In-S and Ga-S bonds. By postheat treatment at 180°C, S atoms were not removed from the surface and band bending was reduced further by 0.1 eV. For AlGaAs, S atoms initially reacted with Ga and As, but this treatment could not remove the Al oxide previously formed in the air. Postheat treatment at 180°C simply induced S redistribution from As to Ga and As desorption, which reduced the band bending by 0.3 eV compared to the sputter-cleaned surface-a result similar to that for GaAs.

Effects of Si3N4passivation on the dc and RF characteristics of metamorphic high-electron-mobility transistors depending on the gate-recess structures

“…On the other hand, in the case of a narrow gate-recess structure, the cap layer is not removed except the gate-foot landing area; therefore, the InAlAs surface states do not dominantly affect the electric potential inside the channel. The reason why the InGaAs free surface state (narrow gate-recess structure) has negligible density compared to the InAlAs surface state (wide gate-recess structure) is not clearly understood; however, one possible cause is related to the Al-O bond on the InAlAs, which is observed in the AlGaAs surface by x-ray photoelectron spectroscopy [27]. This type of Al-O defect on the surface of Al-alloy compound semiconductor is hardly removed even by the sulfur treatment unlike other surface bonds because of its high thermal stability.…”

New value of old knowledge: sulphur-based GaAs surface passivation and potential GaAs application in molecular electronics and spintronics

“…Presently surface passivation topic is quite active in GaAs-related solar cells [15,[33][34][35][36][37], but without any discovery of a permanent solution to the active surface problem [2,38]. Sulfur (S) passivation has been the most promising surface treatment, significantly improving surface electrical properties and drawing considerable attention [39][40][41][42][43][44][45]. The improvement in S passivation also involved a highly controlled atmosphere and high-temperature annealing, yielding ideal surface electrical properties [46][47][48].…”