Laser oscillation with optically pumped very thin GaAs-AlxGa1−xAs multilayer structures and conventional double heterostructures

Optically pumped laser oscillation from multilayer heterostructures (ML) grown by molecular beam epitaxy (MBE) that consist of many alternating thin layers of GaAs and AlxGa1−xAs has been studied in some detail over the temperature range 7–300 K. These samples which have GaAs layers 100–200 Å thick that act as one-dimensional potential wells for electrons and holes have thresholds for lasing that are generally a factor of 2 or more higher than conventional comparable GaAs-AlxGa1−xAs double heterostructures (DH) also grown by MBE. The quantum effects due to the GaAs wells of the ML samples are shown to exist under lasing conditions well above room temperature, but there is no evidence to date of the beneficial effects expected from the modified density of states of this type of structure. Also optically pumped conventional DH lasers grown by MBE and liquid phase epitaxy (LPE) have been compared. The DH lasers grown by MBE are found to have lasing thresholds that are consistently about a factor of 2 higher than their twins grown by LPE.