Individual electron and hole localization in submonolayer InN quantum sheets embedded in GaN

TL;DR

This study explores how electrons and holes localize in submonolayer InN quantum sheets within GaN, revealing temperature-dependent localization effects and nonradiative recombination mechanisms through photoluminescence spectroscopy.

Contribution

It provides new insights into carrier localization and recombination dynamics in submonolayer InN/GaN quantum sheets, highlighting the role of disorder and extended states.

Findings

Carrier localization evidenced by temperature-dependent PL spectra.

Spatial separation of electrons and holes at low temperatures.

Thermally activated quenching linked to extended states in GaN barriers.

Abstract

We investigate sub-monolayer InN quantum sheets embedded in GaN(0001) by temperature-dependent photoluminescence spectroscopy under both continuous-wave and pulsed excitation. Both the peak energy and the linewidth of the emission band associated with the quantum sheets exhibit an anomalous dependence on temperature indicative of carrier localization. Photoluminescence transients reveal a power law decay at low temperatures reflecting that the recombining electrons and holes occupy spatially separate, individual potential minima reminiscent of conventional (In,Ga)N(0001) quantum wells exhibiting the characteristic disorder of a random alloy. At elevated temperatures, carrier delocalization sets in and is accompanied by a thermally activated quenching of the emission. We ascribe the strong nonradiative recombination to extended states in the GaN barriers and confirm our assumption by a simple rate-equation model.