Low temperature photoluminescence study of polycrystalline ZnO

TL;DR

This study investigates the low temperature photoluminescence properties of polycrystalline ZnO, revealing detailed excitonic and phonon-related features, and how these features shift with excitation intensity.

Contribution

It provides new insights into the excitonic and phononic behavior of ZnO at low temperatures, including intensity-dependent peak shifts and dynamics.

Findings

Identification of multiple excitonic peaks at 6K.

Observation of phonon replica and donor-acceptor transitions.

Intensity-dependent red and blue shifts of specific peaks.

Abstract

We report on low temperature photoluminescence study of ZnO. The photoluminescence profile at 6K reveals FXA n=1, FXn=2A and FXn=1B peaks at 367.04 nm, 363.17 nm and 365.66 nm respectively together with neutral donor bound exciton D0 1XA at 370.48 nm. The first, second, and third order longitudinal optical phonon replica of free exciton transitions FXn=1A at 375.03, 383.10, and 391.54 nm respectively, and donor acceptor pair transition at 386.73 nm is observed. The dynamics of D0 1XA and 1LO with excitation intensity is presented. A red shift of photoluminescence peak position of D0 1XA and blue shift of 1LO with increase of pump intensity is observed. The peak photoluminescence intensity of D0 1XA increases superlinearly with increase of pump intensity.