Influence of Al pre-deposition time on AlGaN/GaN heterostructures grown on sapphire substrate by metal organic chemical
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Influence of Al pre‑deposition time on AlGaN/GaN heterostructures grown on sapphire substrate by metal organic chemical vapor deposition Chuanyang Liu1,2 · Jia Wang3 · Yiming Shen3 · Lin Du3 · Yachao Zhang1 · Shengrui Xu1 · Li Jiang2 · Jincheng Zhang1 · Yue Hao1 Received: 11 March 2020 / Accepted: 17 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Aluminum (Al) pre-deposition technology was employed to grow high-quality AlGaN/GaN heterostructures on c-plane sapphire substrates by metal organic chemical vapor deposition. The effects of Al pre-deposition time on the structural and transport properties of the heterostructures were investigated in detail. The optimal Al pre-deposition time was found to be 3 s, and the AlGaN/GaN heterostructures grown under the optimal conditions possessed the surface root mean square roughness of 0.312 nm, threading dislocation density of 1.66 × 109 cm−2, two-dimensional electron gas (2DEG) mobility of 1808.09 cm2/V s and wafer resistance non-uniformity of 0.65%. Further, the influence mechanism of Al pre-deposition time on the dislocation density in the GaN buffer layer was revealed through the research on bare AlN nucleation layer grown on sapphire substrates. The results in this work not only demonstrate the great potential of AlGaN/GaN heterostructures with Al pre-deposition technology in electronic device applications, but also provide practical guidance for the growth of high‐quality group III nitride materials.
1 Introduction AlGaN/GaN-based high electron mobility transistors (HEMTs) have attracted extensive attention for applications in high-power and high-frequency devices due to the extremely high concentration, mobility and saturation velocity of the two-dimensional electron gas (2DEG) near the hetero-interface [1–6]. Moreover, the employment of silicon (Si) doping AlGaN barrier which is carried out by the in situ
doping technology further improves the performance limit of nitride power devices [7, 8]. For the growth of AlGaN/GaN heterostructures, c-plane sapphire is one of the most common substrates due to its low cost, large size and high stability at high temperature [9–12]. However, the large differences in lattice constant and thermal expansion coefficient between the sapphire substrate and GaN epitaxial film can lead to high density of threading dislocations (TDs), which severely deteriorates the device performance. To solve this problem,
* Yachao Zhang [email protected]
Jincheng Zhang [email protected]
Chuanyang Liu [email protected]
Yue Hao [email protected]
Jia Wang [email protected]
1
State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, No. 2 South Taibai Road, Xi’an 710071, China
2
School of Electronic and Information Engineering, Suzhou University of Science and Technology, No. 99 Xuefu Road, Suzhou 215009, China
3
Shanghai Precision Metrology and Testing Research Institute, 3888 Yuanjiang Road, Shanghai 20110
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