Room-temperature band-edge photoluminescence from cadmium telluride

Abstract

Room-temperature photoluminescence (PL) spectroscopy of II-VI semiconductor alloys has been proposed as a useful tool for determination of spatial variations in alloy concentration and impurity concentration. However, the nature of the PL recombination can affect the emission peak energy, as well as line shape. These effects in the band-edge emission of the compound II-VI semiconductor CdTe are reported here. PL measurements at 300 K were recorded from (1) highly doped n-type CdTe films grown by molecular-beam epitaxy, (2) undoped high-resistivity (p-10' -10 0cm) bulk CdTe, and (3) as-grown nominally p-type (p-10 -10' 0 cm) bulk CdTe. The dependence of PL emission intensity and line shape over a range of excitation from 0.003 -70 W/cm was studied. As the excitation power density was increased, a redshift in PL peak position was observed from all samples. PL peak position, intensity, and line-shape analysis show the highly excitonic nature of the radiative recombination in these materials, even though the free-exciton binding energy in CdTe is about 3 of kT at 300 K. In addition, the PL peak position can be more than 7 meV higher from n-type CdTe as compared to undoped CdTe.

The role of transition radiation in cathodoluminescence imaging and spectroscopy of thin-foils

“…The k-values for grain interiors is similar to grain boundaries (Table 1) and is ~1.4, which suggests that the dominant recombination mechanism is exciton-related. The results are consistent with room temperature photoluminescence measurements on p-type CdTe [32]. This is however not to be confused with the well-known behaviour of CdTe at low temperature (i.e.…”

“…5b. The room temperature SEM-CL [10] and photoluminescence [32] spectrum for CdTe consists of a peak at ~820 nm wavelength as well as a high energy tail extending to ~760 nm wavelength. This is evident in Fig.…”

Carrier recombination dynamics in individual CdSe nanowires

“…Previous studies have shown how such measurements can clarify the nature of carriers and their recombination mechanisms in low dimensional systems. [38][39][40][41] As an example, Reference 41 distinguishes free carrier dynamics from excitonic behavior based on the growth order of the emission intensity.…”

Nanometre-scale optical property fluctuations in Cu2ZnSnS4 revealed by low temperature cathodoluminescence

“…In previous studies [34,35] the three peaks have been labelled as BB, BT and BI, although, apart from perhaps the BB peak, there is no unambiguous evidence for such an identification. For a BB transition the peak energy is at (E g + ½kT) [36], i.e. close to the band gap energy E g at low temperatures.…”