Interpretation of Selective Etching of III–V Compounds on the Basis of Semiconductor Electrochemistry

Basic electrochemical processes at GaAs, GaAsP, and GaA1As electrodes were studied in H~O~ aqueous solutions at several pH values. An analytical automatic system, which directly plots gallium concentration vs. potential, allows the collection of information on corrosion processes. The approach of making continuous analysis of gallium ions, while dissolving the semiconductor at a preselected potential, was used in conjunction with impedance and ellipsometric measurements in order to study interfacial phenomena. On the basis of these results, a mechanism for chemical corrosion (etching) which involves electrons captured from semiconductor surface states by H202 was proposed. Anodic polarization can also induce corrosion by hole generation in the valence band or by avalanche breakdown. As expected, pH plays a fundamental role in the corrosion process through the solubility shift of the oxide layer. Further consideration is given to the effect of illumination, with special emphasis on p-type semiconductors, for which it can lead to an inhibition effect on corrosion via a current doubling mechanism. Finally, application of selective etching is described for GaAs, GaA1As, and GaAsP hetero structures.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 141.211.4.224 Downloaded on 2015-06-13 to IP ABSTRACT The catalytic activity for electrooxidation of hypophosphite and electroless nickel plating on iron, nickel, and electrolessly plated nickel (with 2.2-2.9 weight percent (w/o) p) was investigated in an ammoniacal solution ofpH 8.8 at 50~ by potential measurements and linear sweep voltammetry from -0.3V to 0.92Vvs. SCE. Cathodic polarization of any of the substrates (in 0.1M H2SO4) before testing or permeation of hydrogen throughiron foils during testing reduced the incuba-

mentioning

confidence: 99%

Electrochemical and Photoelectrochemical Behavior and Selective Etching of III–V Semiconductors in H 2 O 2 as Redox System

Haroutiounian

Sandino

Cléchet

et al. 1984

“…Oxidation Se = + 2h + ---> Se(~dso~pea) [11] Dissolution Se~aasorp~a) + polyselenide --> longer chain polyselenide [12] Low or no concentrations of added selenium are disadvantageous to n-GaAs/selenide PEC behavior. Another domain to explore is intermediate or high concentration of added Se ~ for enhanced PEC behavior.…”

Section: Resultsmentioning

confidence: 99%

“…1 has been shown to form deep and extensive tunneling in <111> directions in the GaAs bulk I~ and can be significantly enhanced upon illumination. 12 Cachet et al also demonstrated the photoinduced dissolution of illuminated n-GaAs in 1M KOH (pH 14). 13 Measurements of corrosion efficiencies have demonstrated n-GaAs photoanode stabilization via kinetic competition from suitable redox couples.…”

Section: Introductionmentioning

confidence: 96%

Solution‐Modified n ‐ GaAs / Aqueous Polyselenide Photoelectrochemistry

Forouzan

Licht

1995

The effect of aqueous polyselenide solution modification on the photoelectrochemical behavior of n-GaAs/aqueous polyselenide photoelectrochemical cells (PECs) is investigated. Solution modification is achieved through pH control and changing the ratio of dissolved selenium to selenide. Numerical analysis of speciation in various polyselenide solutions is compared to PEC behavior. It is shown that PEC photocurrent, photovoltage, and fill factor are affected by the distribution of hydroselenide, selenide, and polyselenide in solution. There appears to be an optimum pH ([KOH] = 1 to 2M) providing sufficient concentrations of Se = to improve PEC response. A back wall PEC was designed to investigate the high selenium concentration domain not normally accessible to conventional regenerative solar cells. Photopotential is enhanced by up to 50 mV in high [Se ~ electrolytes. However, these electrolytes can diminish photocurrent stability.

“…Some workers [7] have used broad area illumination to enhance photoetching. However, localized illumination creates a higher etch rate due to better carrier separation [8].…”

Section: Resultsmentioning

confidence: 99%

Dopant‐Type Selective Electroless Photoetching of Zn‐Diffused InP and InGaAs / InP Heterostructures

Williamson

Carey

1993