Thermodynamic balance in the modelling of quantum well lasers

Summary form only given. The assumption of quasi-equilibrium within the electron and hole energy distributions is at the heart of most semiconductor laser diode gain theories and is the basis for models used to design and optimise devices. One of the consequences of the existence of such distributions is that there is a known detailed balance relation between the spontaneous emission and gain spectra of excited semiconductor systems. This relation is used explicitly in some theories to derive the spontaneous emission spectrum from the material gain/absorption spectrum to calculate the intrinsic radiative current. The recent development of a segmented-contact, single-pass method for measuring optical gain has enabled us to measure the optical modal gain spectrum, the spontaneous emission and the quasi-Fermi level separation simultaneously under the same pumping conditions. We have measured modal gain and spontaneous emission spectra for segmented-contact GaInP/AlGaInP quantum well structures.