Growth of high-quality GaN by molecular beam epitaxy for the application in high-power and high-frequency electronics

Thi Thu Mai^1*, Jin Ji Dai¹, Ssu Kuan Wu¹, Elica Heredia¹, Sa-Hoang Huynh¹, Wu-Ching Chou¹

¹Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan

* Presenter:Thi Thu Mai, email:maithucs@gmail.com

Abstract: High electron mobility transistors (HEMTs) fabricated using AlGaN/GaN heterostructures grown on Si substrate has gained tremendous attention for high-speed and high-power electronic device applications. However, improving the crystal quality at the interface of AlGaN/GaN heterostructure in order to achieve better device performance remains challenging.
In the current report, the growth of GaN layers by plasma-assisted molecular beam epitaxy (PAMBE) on the metal-organic chemical vapor deposition (MOCVD) GaN/Si templates were studied for improving the crystal quality of the AlGaN/GaN heterostructure. X-ray diffraction and luminescence analysis confirmed the formation of high-quality GaN with significantly reduced threading dislocation density and defects. Low temperature (10K) photoluminescence spectra evidenced the enormously reduced yellow and blue band luminescence intensity, indicating a reduction in point defects and impurities. Atomic force microscopy (AFM) shows a smooth morphology with the root mean square roughness less than 0.5 nm. In addition, the reduced pit density was observed by scanning electron microscopy (SEM). The above results were further verified by the cathode-luminescence measurements.

Keywords: Molecular Beam Epitaxy, two-dimensional GaN, threading dislocations