Shallow donor spectroscopy in GaxIn1-xAsyP1-y

Transitions between the
1s
and
2p
levels of shallow hydrogenic donors have been observed in two samples of high purity Ga
x
In
1-x
As
y
P
1-y
by infrared photoconductivity and transmission. The magnetic field dependence of the shallow hydrogenic levels is found to be very accurately predicted by the use of an effective Rydberg constant
R* = R_{0}(m*/m_{0}\epsilon_{0}^{2})
where the dielectric constant (ε
0
) has been determined by interpolation of the values for the alloy constituents, and the effective mass
m*/m_{0}
is given by the linear interpolation
m*/m_{0} = 0.08 - 0.039y
. At high magnetic fields, the
2p+
level is found to show polaron pinning to the LO phonon associated with a "Ga
x
In
1-x
As"-like alloy.