Indirect—Band-Gap Super-Radiant Laser in GaP Containing Isoelectronic Traps

We report observations which can be interpreted as super-radiant laser emission in the indirect—band-gap semiconductor GaP. Optical gain, as high as ${10}^4$ ${\mathrm{cm}}^{-1\mathrm{}}$ at 2°K, has been measured over a range of temperatures from 2 to 300°K. The gain arises from a new process not important at low excitation intensities. It is demonstrated that isoelectronic traps are an important part of this new process.