Applied Physics Letters · 1996 · 34 citations · 0 references
Natural SciencesMaterials EngineeringMaterials ScienceElectronic MaterialsOptoelectronicsSemiconductor MaterialsElectronic Band StructureLaser Host MaterialsLaser PhysicsOptical Properties Of SemiconductorsOptical Properties Of SolidsSemiconductor LasersCrystal DopingCrystal Host MaterialsDuty Cycle EffectsIntervalence Absorption BandsLaser Gain MaterialsLaser Pulse DurationLasersRadiation Absorption
We report on intervalence-band laser emission from Be- and Zn-doped germanium crystals. The duty cycle of 10−3 at a repetition rate of 1 kHz is one order of magnitude larger than the highest duty cycle reported for p-Ge lasers doped by group II acceptors. This improvement is due to the much larger hole binding energy of double acceptors Be and Zn which results in a strong reduction of the internal absorption of the generated far-infrared radiation. Laser action has been achieved with crystal volumes as small as 0.04 cm−3, and a laser pulse length of 25 μs has been reached. Germanium crystals doped with these acceptors may offer an opportunity for achieving the ultimate goal of continuous wave operation.