Advantages of InGaN/GaN multiple quantum wells with two-step grown low temperature GaN cap layers. (November 2017)

• Record Type: Journal Article
• Authors: Zhu, Yadan; Lu, Taiping; Zhou, Xiaorun; Zhao, Guangzhou; Dong, Hailiang; Jia, Zhigang; Liu, Xuguang; Xu, Bingshe
• Is Part Of: Superlattices and microstructures. Volume 111(2017)
• Page Start: 960
• Page End: 965
• Publication Date: 2017-11
• Subjects: GaN cap layer -- Quantum wells -- Hydrogen -- InGaN; Superlattices as materials -- Periodicals; Microstructure -- Periodicals; Semiconductors -- Periodicals; Superréseaux -- Périodiques; Microstructure (Physique) -- Périodiques; Semiconducteurs -- Périodiques; 621.38152
• DOI: 10.1016/j.spmi.2017.07.054
• Languages: English
• ISSNs: 0749-6036

Abstract

Abstract: Two-step grown low temperature GaN cap layers (LT-cap) are employed to improve the optical and structural properties of InGaN/GaN multiple quantum wells (MQWs). The first LT-cap layer is grown in nitrogen atmosphere, while a small hydrogen flow is added to the carrier gas during the growth of the second LT-cap layer. High-resolution X-ray diffraction results indicate that the two-step growth method can improve the interface quality of MQWs. Room temperature photoluminescence (PL) tests show about two-fold enhancement in integrated PL intensity, only 25 meV blue-shift in peak energy and almost unchanged line width. On the basis of temperature-dependent PL characteristics analysis, it is concluded that the first and the second LT-cap layer play a different role during the growth of MQWs. The first LT-cap layer acts as a protective layer, which protects quantum well from serious indium loss and interface roughening resulting from the hydrogen over-etching. The hydrogen gas employed in the second LT-cap layer is in favor of reducing defect density and indium segregation. Consequently, interface/surface and optical properties are improved by adopting the two-step growth method. Highlights: Two-step grown low temperature cap layers are employed to improve the quality of active region. Surface and interface properties are improved when the two-step growth method is adopted. Room temperature photoluminescence intensity enhances by about 2-times, while peak energy and line width are almost unchanged by using the two-step growth method.