Production of Defects in InSb by X Rays

Changes in the low-temperature electrical and thermal resistance of InSb were measured at liquid-nitrogen and liquid-helium temperatures as a function of x irradiation (100 kV peak, 12 mA, W target). The direction and asymptotic behavior of the changes on x irradiation are analogous to those produced by fast-electron irradiation and indicate bulk damage. X irradiation of originally $p$-type InSb produces the same changes as x irradiation of InSb that has been converted to $p$ type by electron bombardment. The changes are not due to surface effects, since any surface changes due to ionization would have been saturated by prior electron irradiation. The photoelectrons produced by the soft x rays have energies much lower than the threshold displacement energies for a direct collision process and indicate that displacements are produced by an ionization process which may be similar to the Varley mechanism for ionic crystals. Annealing measurements of the x-ray-induced damage show that the damage almost completely anneals near 102°K.