Band gap energy fluctuations in InGaN films grown by RF‐MBE with changing nitrogen supply rate investigated by a piezoelectric photothermal spectroscopy

Abstract

In this study, non‐radiative recombination center in InGaN films with varying III/N ratio grown by rf‐molecular beam epitaxy was investigated directly by piezoelectric photothermal spectroscopy (PPTS). To clarify the influence of the III/N supply ratio during the InGaN layer growth, the nitrogen flow rate was changed from 1.0 to 2.0 sccm. Since metallic‐indium droplets and phase separation were observed for the samples grown by low nitrogen flow rate, it was found that these have been grown under a group‐III‐rich condition. With increasing nitrogen flow rate, the indium content in InGaN films increased. The estimated non‐radiative recombination edges determined from PPTS method (PPT edge) red‐shifted with increasing the nitrogen flow rate. The energy difference between estimated band edge and the PPT edges increased with increasing flow rate under group‐III rich condition, and became saturated under the N‐rich condition. It is considered that the existence of the phase separation is related to this behavior. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Structural, electrical and optical characterization of MOCVD grown In-rich InGaN layers

“…These result in a solid-state miscibility gap limiting the InN mole fraction in InGaN layers [8,9]. In general, InGaN layers have been grown so far by two different growth techniques: Molecular Beam Epitaxy (MBE) [10] and Metal Organic Chemical Vapor Deposition (MOCVD) [11]. Due to the ineffective cracking of NH 3 at the required low growth temperature of InGaN layer, employing MOCVD is more challenging.…”