Photoluminescence and optical absorption studies of the effects of heat treatment on cuprous oxide

Abstract

The defects responsible for the short-wave (720 nm) and medium-wave (820 nm) luminescence in cuprous oxide can be created by annealing the crystal at a temperature of 1050 °C under low oxygen pressures. The annihilation of these defects has been observed from the photoluminescence and optical absorption measurements after the crystal has been subjected to a second annealing in the temperature range of about 750 °C under a reducing atmosphere. From the photoluminescence measurements, the density of these defects is found to decrease exponentially as a function of annealing time, as manifested by the reduction in the luminescent intensity. The rate of reduction in intensity is also found to increase with annealing temperature.Because the defects responsible for the luminescence are ascribed to various forms of oxygen vacancies, we believe the decrease in luminescence is due to a reduction in the oxygen vacancies resulting from the formation of copper precipitates in the crystal. The short-wave and medium-wave emissions, which are ascribed to different types of oxygen vacancies, are found to have different activation energies of diffusion.

Low Temperature Chemical Vapor Deposition of Cuprous Oxide Thin Films Using a Copper(I) Amidinate Precursor

“…Using the least number of Gaussian bands to fit the PL spectrum, the best fitting result consists of six PL situated at 1.67 eV (744 nm), 1.60 eV (777 nm), 1.52 eV (817 nm), 1.43 eV (870 nm), 1.35 eV (917 nm), and 1.27 eV (973 nm), respectively, as shown in Figure c. Well-known transitions include the 1.67 eV peak originating from the doubly charged oxygen vacancy ( V O 2+ ), the 1.52 eV peak corresponding to the singly charged oxygen vacancy ( V O + ), and the 1.35 eV emission from the transition involving the copper vacancy ( V Cu ). − No signal was observed between 600 and 1000 nm when PL measurements were performed on the blank substrates. Peaks at 1.60, 1.43, and 1.27 eV remain unidentified and warrant further investigation.…”

Decay and coherence of two-photon excited yellow orthoexcitons inCu2O

“…The experiments described here use excitation in the near infrared, where the optical penetration depth is larger than 500 µm. 16 Any contribution due to surface enhanced Auger processes is therefore expected to be negligible. For the same reason (large penetration depth) the thus created exciton gas in nearly uniformly distributed in the sample.…”

Effects of internal potential barriers on the photocurrent decay in semiconductors

“…From the experimental results of process can be explained neither in terms of-the Surnev (1 2), Vorobev and Karhkhanin ( 13), and the Poole-Frenkel effect alone nor by phonon-assisted results of our experiments, this situation should be tunnelling. The electric field strength is too small and expected to occur-at temperatures below 423 K. This explains the occurrence of trapping levels at 1.18 and 1.08 eV for type A samples instead of at 1.33 eV, which is the value expected from the photoluminescence results (2).…”

“…The existence of well-defined large defects of the Schottky barrier type in some semiconductors (these defects can be easily induced in Cu20) has led us to conduct experiments on detrapping in Cu20 to see if any new or unique process is associated with this type of defect. Previously, it has been found that the presence of metallic precipitates in Cu20 affects both the optical (1,2) and the electrical (3) properties of the samples.…”