Temperature-dependent fine structure splitting in InGaN quantum dots

Abstract

We report the experimental observation of temperature-dependent fine structure splitting in semiconductor quantum dots using a non-polar (11-20) a-plane InGaN system, up to the on-chip Peltier cooling threshold of 200 K. At 5 K, a statistical average splitting of 443 ± 132 eV has been found based on 81 quantum dots. The degree of fine structure splitting stays relatively constant for temperatures less than 100 K, and only increases above that temperature. At 200 K, we find that the fine structure splitting ranges between 2 ~ 12 meV, which is an order of magnitude higher than that at low temperatures. Our investigations also show that phonon interactions at high temperatures might have a correlation with the degree of exchange interactions. The large fine structure splitting at 200 K makes it easier to isolate the individual components of the polarized emission spectrally, increasing the effective degree of polarization for potential on-chip applications of polarized single photon sources.