Photoluminescence and optical absorption edge for MOVPE‐grown InN

Abstract

This paper reports the photoluminescence (PL) spectra and the optical absorption edge at room temperature for MOVPE grown InN films as a function of growth temperature and background carrier concentration. A strong PL band with a peak energy in the range 0.7-0.9 eV is observed at room temperature. A sample grown at around 600 °C shows the highest PL intensity and the lowest peak energy. With decreasing the growth temperature from 600 °C, the PL intensity is markedly decreased and the peak energy is shifted toward the higher energy side. The absorption edge shows a similar change with the PL peak energy when the growth temperature is decreased. The difference between absorption edge and the PL peak energy is 50-100 meVand it increases with increasing the carrier concentration. The changes in PL peak energy and absorption edge with carrier concentration are not so steep compared to the absorption edge change predicted by Davydov et al. This may be explained by the increase in electron effective mass with increasing the carrier concentration reported by Wu et al. [Phys. Rev. B 66, 201403 (2002)].

Growth of InN by vertical flow MOVPE

“…No change in the PL spectra was observed with different V/III ratios (spectra not shown here). The blue-shift of the PL peak energy with decreasing growth temperature is thought to result from the increase of carrier concentration in material grown at low temperature [16].…”

Correlations between electrical and optical properties for OMVPE InN

“…Such an OMVPE film with relatively good electrical properties has been used for the band gap study of InN [8,9]. A sample grown at the optimum growth temperature, 600 C, shows a bright photoluminescence (PL) at room temperature with a peak energy of 0.7 eV [10]. In this paper, we report electrical and optical properties of OMVPE InN grown at a different temperature.…”

On the crystalline structure, stoichiometry and band gap of InN thin films

“…For over a decade it had been accepted that the band gap of InN was 1.9 eV. However, recent measurements on high quality InN films with low electron concentrations (<10 19 /cm 3 ) and high mobilities (>100 cm 2 /V⋅s) grown by molecular beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOCVD) have unambiguously agreed upon a fundamental band gap of 0.70±0.05 eV [2][3][4]. This new small gap for InN was further supported by recent ultrafast differential transmission measurements performed on MBE-grown material [5].…”