Abstract
Direct experimental evidence of band-gap shrinkage due to the presence of impurities in semiconductors is given. Experimental results are obtained using a piezomodulation-spectroscopy technique over the (4-300)°K temperature range. They are interpreted in the linear-screened-potential and effective-mass approximations. Coupling spectroscopic and helium-temperature magnetotransport measurements allowed us to obtain in this model a good description of the transition edges over the entire temperaure range. We studied different GaSb samples with impurity concentration allowing us to observe band-gap shrinkage with one and two types of carriers. This is easily obtained in the GaSb case whose band structure presents and minima located very near in energy. On heavily doped samples, the low-temperature values of the band-gap shrinkage are used to obtain further informations concerning subsidiary minima. On lightly doped semiconductors, non- -conserving transitions initiating on the residual acceptor level are clearly shown.
- Received 12 September 1974
DOI:https://doi.org/10.1103/PhysRevB.11.2251
©1975 American Physical Society