Hall coefficient and resistivity measurements as a function of temperature have been made on both $n$- and $p$-type single crystalline samples of InSb after successive periods of exposure in the Oak Ridge graphite reactor. Effects due to the introduction of Sn, a donor impurity, were minimized by shielding the specimens from those neutrons leading to In transmutation with cadmium and indium foil. The results of these measurements indicate conclusively that lattice defects produced by fast-neutron bombardment convert $p$-type InSb to $n$ type. In addition they appear to act as shallow electron traps in $n$-type material. The mobility of carriers is markedly decreased by the bombardment-produced defects, but this decrease in mobility, as well as changes in carrier concentration resulting from bombardment-produced energy states can be essentially completely removed by appropriate heat treatment. An attempt has been made to correlate the various possible simple defects expected in the InSb structure with the nature of energy levels introduced by fast-neutron bombardment.

• Received 3 May 1954

DOI:https://doi.org/10.1103/PhysRev.95.1177