DIRECT OBSERVATION OF THE EXCESS LIGHT HOLE POPULATION IN OPTICALLY PUMPED p-TYPE GERMANIUM

Abstract
We report the direct observation of conductivity modulation by heavy‐to‐light hole transitions in p‐type germanium. The resistance of a p‐type germanium bar was modulated by microsecond pulses of 10‐μ radiation from a Q‐switched CO2 laser. An estimate of the fast carrier lifetime is 10−12 sec. Direct observation of 20‐Mc ringing on the laser pulse is reported. The band‐to‐band type of transition permits room temperature operation.