Influence of process variations in the etching of germanium with hydrogen peroxide has been studied, along with damage effects due to radiation. The work advances the knowledge of the etching process for germanium

Dayal, Y.

Kampwirth, R.

Primak, W.

English

NASA Technical Reports Server

December 1968
	
Brief 68-10454 
•
ICY C
AEC-NASA TECH BRIEF 
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
application. Tech Briefs are published by NASA and may be purchased, at 15 cents each, from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Hydrogen Peroxide Etching Proves Useful for Germanium 
The influence of process variations in the etching of 
germanium with hydrogen peroxide has been studied, 
along with damage effects due to radiation. The 
work advances the knowledge of the etching process 
for germanium and provides information on the in-
fluence of pH, radiation, and pre-etching conditions. 
Etching with 3 percent hydrogen peroxide is useful 
for removing fractional micron layers of germanium. 
Previous experimenters have used the technique to 
remove thin layers for determining ranges in ion bom-
bardment. In the present study, the peroxide etching 
technique was adopted primarily to determine the 
depth of the electrical conductivity change produced 
by ion bombardment. 
Results of this investigation showed that the etching 
rate is insensitive to concentration, but that it is 
sensitive to pH, yielding a minimum of about 0.021 
micron/minute at pH 4, the region recommended for 
controlled etching experiments. The large pH effect 
on the peroxide etching rate of germanium indicates 
that the etching is largely controlled by the solubility 
of the amphoteric oxide surface layer. The etching 
rate was also found to be sensitive to temperature, 
showing a change of a factor 2 from 20° to 30°C, 
and to some foreign ions. For example, the rate is 
about twice as great when sulfate ions are present in 
the solutions as when phosphate ions are present. 
Mechanically polished surfaces exhibit an enhanced 
etching rate. This enhancement is removed by heavy-
ion bombardment, but not by light-ion bombardment. 
The etching rate of normal germanium surfaces is not 
affected appreciably by heavy-ion bombardment, but 
the etch pit density is greatly increased. 
Notes: 
I. A study of the etching of germanium with hydro-
gen peroxide has been presented by W. Primak, R.
Kampwirth, and Y. Dayal in a report entitled 
"Peroxide Etching of Germanium," July 1966. The 
report includes a complete discussion of the results, 
recommendations for etching, and microinterfero-
grams of the etched surfaces. 
This information may be of interest to electronics 
industries, specifically those working with semicon-
ductors. 
Reference: Additional details are contained in the 
Journal of the Electrochemical Societ y , vol. 114, 
no. I, p. 88-91 (January 1967). 
Inquiries concerning this innovation may be di-
rected to:
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B68-10454 
Source: W. Primak and R. Kampwirth 
of Solid State Science Division,
and Y. Dayal
of ANL—IIT
Argonne National Laboratory
(ARG-10170) 
Patent status: 
Inquiries about obtaining rights for commercial use 
of this innovation may be made to: 
Mr. George H. Lee, Chief 
Chicago Patent Group 
U.S. Atomic Energy Commission 
Chicago Operations Office 
9800 South Cass Avenue 
Argonne, Illinois 60439
Category 03 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son acting on behalf of the United States Government assumes any
liability resulting from the use of the information contained in this 
document, or warrants that the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
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Hydrogen peroxide etching proves useful for germanium

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