Mechanisms of infrared photoluminescence in HgTe/HgCdTe superlattice

Temperature (11-250 K) and excitation power (5-480 mW) dependent infrared photoluminescence (PL) measurements are conducted on a HgTe/Hg0.05Cd0.95Te superlattice (SL) sample in a spectral range of 5-18 mu m with adequate spectral resolution and signal-to-noise ratio. Three PL components are identified from the evolution of the PL lineshape with temperature although the full-width at half-maximum (FWHM) of the whole PL signal is only about 7meV at 11 K, for which different changes of the energy, FWHM, and integral intensity are evidenced. The mechanisms are clarified that the medium-energy component is due to electron-heavy hole intersubband transition, while the low-energy (LE) component correlates to localized states and the high-energy (HE) one may originate in interfacial inhomogeneous chemical intermixing and Brillouin-zone boundary effects. The LE and HE component-related effects are responsible for the PL quality of the SL at the temperatures well below and above 77 K, respectively. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4752869]