High Magnetic Field Studies of Confined Impurities in Semiconductors

Abstract

The combination of far infrared spectroscopy and high magnetic fields has proven to be a powerful tool in the study of the electronic properties of bulk semiconductors. Recent advances in growth techniques have permitted the reproducible fabrication of repeated semiconductor heterostructures with interface abruptness on an atomic scale and a very high degree of doping control. Simple considerations show that the electronic states of shallow impurities in such confining structures can depend strongly on location with respect to confining barriers. Recent far infrared magnetospectroscopy studies of shallow donors doped in the GaAs wells of GaAs/AlGaAs multiple quantum well structures are reviewed. Multiple quantum well samples with quantum well widths between 80A and 450Å and doped in the well centers, well edges, and simultaneously in the barrier and well centers have been investigated. Results are in generally good agreement with recent theoretical calculations. Possible use of such measurements to determine the impurity distribution along the growth direction is discussed.