The effect of high pressure on S and Te-doped GaAs1-xPx
Craford, Magnus George
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https://hdl.handle.net/2142/25717
Description
Title
The effect of high pressure on S and Te-doped GaAs1-xPx
Author(s)
Craford, Magnus George
Issue Date
1967
Doctoral Committee Chair(s)
Lazarus, David
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
electrical resistivity
n-doped
s-doped
Language
en
Abstract
The pressure dependence of the electrical resistivity of
n-type GaAs l -x Px is measured to a pressure of 7 kilobars at temperatures
of 770, 195
0 , and 300
0
K. The samples are doped with sulfur and
tellurium and have carrier concentrations in the 10^18 - 10^19
range. Changes in the resistivity as large as four orders of magnitude
are observed at 77 0K for samples in the composition range 0.30 ~ x ~ 0.4~
The behavior of the samples is consistent with a model in which the
higher lying [lOOJ conduction band edge has associated with it a donor
level which is deep with respect to the [lOOJ minima. The level depth
with respect to these minima is found to be 0.03 eV for Te-doped
crystals, and ~ 0.06 eV for S-doped crystals.
The S-doped samples also exhibit a light-sensitive, longlifetime
trapping behavior. The trapping appears to be associated
with an additional deep level which moves away from the [OOOJ conduction
band minimum at the ratJ of approximately 10.8 x 10-3 eV/kbar. The
data indicate that this trapping level is probably a second split-off
level associated with and - 0.16 eV below the
The mobility ratio of the two bands
[equation] is found to be
15-30 at 3000K and 1950K but is found to increase to 60-100 at 77 0 K.
The phosphorus concentration x at which the [OOOJ and [lOOJ minima
are equal in energy appears to be x ~ 0.43 at 77 0K and x ~ 0.45 at
3000 K, implying that the separation between the minima increases
with temperature at the rate of ~ 6 x 10-5 eV/oK. It is verified by
combining resistance vs. pressure curves for samples of different
composition x that increasing the pressure and increasing x have a
similar effect on the band structure of the GaAs1-xPx system.
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