Electrolytic etching and electron mobility of GaAs for FET's

A new solution system consisting of H3PO4, H202, and H20 was found useful for etching GaAs wafers. This solution system can be divided into four regions a-d, according to etching characteristics. The boundaries between the regions are given by a rfiole ratio (m 9 r) of H202 to HsPO4 of about 2.3 and a mole fraction (m 9 5) of H20 of about 0.9 at room temperature. Ratelimiting processes are: a, adsorption of H202 (m. r <_ 2.3, m. ] ~ > 0.9)', b, diffusion of H202 (m 9 r <~ 2.3, m 9 ] < 0.9) ; c, dissolution of oxidized products (m-r > 2.3, m-] <_ 0.9); and d, adsorption of H~PO~ (~-r _ > 2.3, m. ] > 0.9). Solutions in region a have a reproducible etching rate of 0.01-0.1 ~m/min, which is useful for MESFET processing. Crystallographic etching is also available with solutions in region c.

Section: Resultsmentioning

confidence: 94%

mentioning

confidence: 99%

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A New Etching Solution System, H 3 PO 4 ‐ H 2 O 2 ‐ H 2 O , for GaAs and Its Kinetics

Mori

Watanabe

1978

“…Rode et al (92) showed that this severe pitting could be minimized by performing the anodic etching in two stages. This can often result in a severely pitted surface; in extreme circumstances, the membrane can actually etch through in places.…”

Section: Fig 7 the Formation Of Membranes Using The Resistivity Gramentioning

confidence: 99%

The Fabrication of Thin, Freestanding, Single‐Crystal, Semiconductor Membranes

Lee¹

1990

Freestanding, single-crystal, semiconductor membranes with thicknesses in the range of a few tens of nanometers to tens of microns are of increasing technological interest today. Their applications range from high speed electronic devices to electromechanical devices and pressure sensors. This review paper identifies two general classes of techniques for producing such thin membranes: dissolution of single-crystal wafers, and direct growth of single-crystal membranes. Numerous specific techniques in each general class are discussed. The discussion of each technique includes a brief explanation of the reason why it works, a description of the actual experimental implementation, an analysis of the range of thickness that can be produced, and the crystalline and electrical quality of the membranes. Unusual difficulties with implementing a technique, or special advantages of a technique are also noted. Since this review is intended to aid in the selection of a technique for producing thin semiconductor membranes when one has a particular application in mind, note is made of those applications for which the membranes produced with each technique are particularly well suited. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.197.26.12 Downloaded on 2015-06-27 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.197.26.12 Downloaded on 2015-06-27 to IP

“…Behavior of Jf and Jl in arbitrary units derived from the ~-t curve inFig, 6and Eq [3]. in the text.…”

mentioning

confidence: 99%

Anodization of Layered Semiconductors: A Representation of the Layer Periodicity

Moritani

Kubo

Nakai

1979

Anodization of layered semiconductors, especially Bi2Te3 and GaSe, has been done to have a new representation of the layer periodicity which the layered semiconductors possess as their peculiar property. Constant current anodization (c.c.a.) in a solution of sodium borate in ethylene glycol (GSE) at pH 7 has been mainly adopted since the periodic surface condition for the successive monolayer film formation can be maintained by c.c.a, and GSE has been found to be an excellent electrolyte for the representation of the layer periodicity in these semiconductors. The layer periodicity has been represented by the periodically varying structures observed in the cell voltage vs. time (Vc-t) and its second derivative (--d2Vc/dt2-t) curves for Bi2Te3, Bi2Se3, GaTe, and GaSe, and in the in situ ellipsometric off-null signal vs. time (AI-t) curves for Bi2Tes in c.c.a. Unit line shapes of the Vc-t and the surface coverage vs. time (0-t) curves derived from AI-t curves have been investigated to understand the anodization process for the monolayer film formation in Bi2Te3 where the two-dimensional nucleation and growth, which may result from a suppressed growth in the perpendicular direction to the cleavage surface by the potential barrier at the layer boundary, are taking place with the slow step of competing rate-determining processes with comparable rates. The competing rate-determining processes have been also recognized by the current transients in the potentiostatic anodization of Bi2Te8 in GSE on the analogy of the electrocrystallization study on nickel reported by Fleischmann et al. It has turned out in c.c.a, of GaSe in GS~ that insoluble nonpassive films grow two dimensionally in the initial stage of anodization and transform into passive films. Another interesting observation has been made in the transient 'behaviors of --d2Vc/dt2-t characteristics.They have been classified into five types, depending on the kind of electrolytes and semiconductor samples used, or on being related to the current efficiency, the rate-determining process and/or transformation from three-dimensional to two-dimensional growth of passive films.Anodization of semiconductors has been applied to measurements on the depth profile of the carrier concentration (1) and of the alloy composition of GaAsz-xPx (2) and for control of thickness of epitaxial layer on GaAs (3), utilizing the property that thickness of anodically grown films is highly and easily controllable. As a new approach of application, we have shown in the previous paper (4) that periodically varying structures reflecting the layered structure of the layered semiconductors were observed in the cell voltage vs. time (Vc-t) curves when anodization was carried out under a proper constant current condition (c.c.c.) with the use of a proper electrolyte as shown in Fig. 1 for Bi2Tes, and these periodic structures have enabled us to count the number of layers with a mono!ayer thickness of around 10A since the unit line shape from which the periodic structure in the Vc-t curves is construc...