Optical properties of a-plane InGaN/GaN multiple quantum wells on r-plane sapphire substrates with different indium compositions

Abstract

In x Ga 1−x N / GaN ͑x = 0.09, 0.14, 0.24, and 0.3͒ multiple-quantum-wells ͑MQWs͒ samples, with a well width of about 4.5 nm, were achieved by utilizing r-plane sapphire substrates. Optical quality was investigated by means of photoluminescence ͑PL͒, cathodoluminescence, and time resolved PL measurements ͑TRPL͒. Two distinguishable emission peaks were examined from the low temperature PL spectra, where the high-and low-energy peaks were ascribed to quantum wells and localized states, respectively. Due to an increase in the localized energy states and absence of quantum confined Stark effect, the quantum efficiency was increased with increasing indium composition up to 24%. As the indium composition reached 30%, however, pronounced deterioration in luminescence efficiency was observed. The phenomenon could be attributed to the high defect densities in the MQWs resulted from the increased accumulation of strain between the InGaN well and GaN barrier. This argument was verified from the much shorter carrier lifetime at 15 K and smaller activation energy for In 0.3 Ga 0.7 N / GaN MQWs. In addition, the polarization-dependent PL revealed that the degree of polarization decreased with increasing indium compositions because of the enhancement of zero-dimensional nature of the localizing centers. Our detailed investigations indicate that the indium content in a-plane InGaN/GaN MQWs not only has an influence on optical performance, but is also important for further application of nitride semiconductors.

Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

“…Furthermore, while the DOLPs of a-plane quantum wells (QWs) are limited to ~0.60 [26], we report a much higher average DOLP of ~0.90 in a-plane InGaN QDs. Previous investigations have reported polarization properties of some a-plane InGaN QDs along [0001] [27], orthogonal to those reported in a-plane QWs (along ) [26,28,29]. We find that this is a special case to the general behavior of a-plane QDs.…”

Heteroepitaxial growth of InN on GaN intermediate layer by PA-MOMBE

“…Previous literatures have reported that the carriers could receive activation energy to thermalize from potential minima to nonradiative or delocalized centers as the temperature was increased. To get insight into the thermal quenching process associated with the localized states, the PL intensity as a function of temperature was studied, and the experimental temperature-dependent PL data were fitted by Arrhenius equation to investigate the carrier behavior during the thermal processes [14] IðTÞ…”

Optical properties of (1 1¯ 0 1) semi-polar InGaN/GaN multiple quantum wells grown on patterned silicon substrates

“…It means the InGaN/GaN MQWs grown on (1 1 0 1) GaN/7 degrees off axis (0 0 1) Si substrate have very low internal piezoelectric field and this leads to the decrease of QCSE [22]. The integrated PL intensity was fitted based on the relation I $ P a [23], where I is the integrated PL intensity, P is the excitation power density, and a is the power index. The fitting result is shown in Fig.…”