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Evolution of InAs quantum dots and wetting layer on GaAs (001): Peculiar photoluminescence near onset of quantum dot formation
摘要： InAs quantum dots (QDs) have been grown on a GaAs (001) substrate in the subcritical region of InAs coverage for transition from a 2-dimensional (2D) to a 3-dimensional growth mode. Evolution of QDs and the corresponding wetting layer (WL) with InAs coverage has been investigated. Under specific growth conditions, quantum dot formation was observed only in samples where InAs coverage is more than 1.48 ML. The QD density increases sharply with InAs deposition initially but slows down with increased coverage. Photoluminescence (PL) shows the existence of a third peak, other than QD and WL peaks, at the low energy side of the WL peak, which is named the precursor peak. Evidence is presented supporting the theory that this peak is due to 2D InAs islands on a monolayer of InAs, which are small enough to localize excitons. Meanwhile, the WL peak is due to larger InAs islands under high compressive strain. During QD formation, the WL peak energy increases with the increase in InAs deposition. This is due to the sudden transfer of material from the bigger size of InAs islands to the QD. Our results show that the QD, WL, and precursor peaks coexist near the onset of QD formation. The power dependence of the three PL peaks is evident, which supports to our conclusion.
关键词： precursor peak,InAs quantum dots,wetting layer,photoluminescence,GaAs substrate
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 4th Optoelectronics Global Conference (OGC) - Shenzhen, China (2019.9.3-2019.9.6)] 2019 IEEE 4th Optoelectronics Global Conference (OGC) - Quality Assessment of 980 nm GaAs Based Laser Diodes with Use of Low-Frequency Noise Measurements
摘要： Low-frequency noise has always been a fast and non-destructive tool to characterise the performance and quality of materials and electrical devices. In this paper, a non- destructive method of predicting reliability was introduced for 980 nm GaAs based semiconductor laser diodes. Measurement and analysis were carried out for the noise and transport characteristics of forward voltage biases. The results demonstrated a close relationship between LD quality and the characteristic parameters of low-frequency noise such as frequency exponent, noise intensity and amplitude.
关键词： low-frequency noise,frequency exponent,forward bias,laser diodes,GaAs substrate
更新于2025-09-16 10:30:52
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InAs on GaAs Photodetectors Using Thin InAlAs Graded Buffers and Their Application to Exceeding Short-Wave Infrared Imaging at 300?K
摘要： Short-wave infrared (SWIR) detectors and emitters have a high potential value in several fields of applications, including the internet of things (IoT) and advanced driver assistance systems (ADAS), gas sensing. Indium Gallium Arsenide (InGaAs) photodetectors are widely used in the SWIR region of 1–3 μm; however, they only capture a part of the region due to a cut-off wavelength of 1.7 μm. This study presents an InAs p-i-n photodetector grown on a GaAs substrate (001) by inserting 730-nm thick inxAl1?xAs graded and AlAs buffer layers between the InAs layer and the GaAs substrate. At room temperature, the fabricated InAs photodetector operated in an infrared range of approximately 1.5–4 μm and its detectivity (D*) was 1.65 × 108 cm · Hz1/2 · W?1 at 3.3 μm. To demonstrate performance, the Sherlock Holmes mapping images were obtained using the photodetector at room temperature.
关键词： InxAl1?xAs graded buffer,InAs p-i-n photodetector,GaAs substrate,room temperature operation,Short-wave infrared (SWIR),InGaAs photodetectors
更新于2025-09-11 14:15:04