Temperature dependent exciton photoluminescence of bulk ZnO

Abstract

Temperature dependent (4.2–300 K) photoluminescence (PL) of bulk (0001)-oriented ZnO in the range of free- and bound-exciton emission is presented. Emission from several bound excitons and the free A exciton were observed from the low temperature (20 K) PL spectrum. The temperature dependence of the free-exciton peak position was fit using the Manoogian-Woolley equation and the coefficients obtained show reasonable agreement both with first-principle theoretical calculations and empirical values of the coefficients for other II–VI semiconductors. The strongest bound-exciton line with a width (full width at half maximum) of about 1 meV exhibited a thermal activation energy of approximately 14 meV, consistent with the exciton-defect binding energy. It was not observed at temperatures above 150 K. Additional analysis of this particular bound-exciton peak suggests it dissociates into a free exciton and a neutral-donor-like defect-pair complex with increasing temperature.

Photoluminescence Study on O-plasma Treated ZnO Thin Films

“…Peak I in Fig. 1, appearing at 3.360 eV for both samples (as grown and O-plasma treated), is believed to be mainly the recombination of D 0 X, which is in good agreement with the results reported by other groups [12][13][14][15].…”

“…We believe that this peak comes from the decay of the free exciton, considering the relative position of the peak to D 0 X along with characteristic features of temperature evolution. The localization energy of bound excitons in ZnO is known to be 10-20 meV [12,14,15,20], which is in a good agreement with our result. This indicates that bound excitons change into free excitons as the temperature increases.…”

Exciton Drift in Semiconductors under Uniform Strain Gradients: Application to Bent ZnO Microwires

“…More precisely, the CL spectrum of the straight segment shows a dominant transition from neutral donor-bound exciton (3.360 eV, D 0 X A ), with additionally the two-electron satellite (3.324 eV, TES) and the LO phonon replica of D 0 X A (3.292 eV). 30,31 There is no change when moving the spot across the MW (see Figure 1d). In the pure bending segment, on the contrary, the luminescence spectrum depends on the excitation position (see Figure 1f).…”

Production and recovery of defects in phosphorus-implanted ZnO

“…For the unimplanted ZnO, there is a band-edge ultraviolet (UV) emission peak located at 3.3 eV, which is due to the recombination of free excitons. 2,[39][40][41] The deep level emission is rather weak and nearly invisible. Either there are few deep level centers, or there are nonradiative recombination centers that have suppressed the deep level emission.…”