Far-infrared laser oscillation from a very small p-Ge crystal under uniaxial stress

We report on pulse laser oscillation from a p-Ge intervalence band (IVB) la ser composed of a Ga-doped Ge crystal measuring about 1 x 1 x 5 mm(3) which is a very small volume compared with those reported so far for shallow-acc eptor-doped Ge. Laser oscillation is only achieved under uniaxial stresses greater than 1300 kg/cm(2). We find that the optimum stress for lasing is a round 3500-4100 kg/cm(2) when the p-Ge IVB lasers are operated at liquid he lium temperature. The minimum electric power needed for lasing is only 280 W at a peak period of pulse emission. (C) 1999 American Institute of Physic s. [S0003-6951(99)01823-9].