Optical studies of GaInP/GaP quantum dots

The capped self-assembled GaxIn1−xP/GaP quantum dots grown by low-pressure metalorganic vapour phase epitaxy on selenium doped GaP substrates have been investigated by continuous wave (CW) and time resolved photoluminescence (PL). The dependence of the dot PL with respect to varying growth temperature and gallium composition has been examined and compared with atomic force microscopy results obtained on similar uncapped samples. Surprisingly, the results indicate that the optical characteristics of the dots are almost independent of the sample growth temperature and nominal gallium content. This result is thought to be due to the fact that the islands undergo a phase separation process forming In-rich dots surrounded by Ga-rich base layers. Temperature dependent continuous wave (CW) PL measurements, as well as temperature dependent and excitation power density dependent, time resolved PL experiments have been performed and support this hypothesis.