tailieunhanh - Báo cáo hóa học: " Microstructure of non-polar GaN on LiGaO2 grown by plasma-assisted MBE"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Microstructure of non-polar GaN on LiGaO2 grown by plasma-assisted MBE | Shih et al. Nanoscale Research Letters 2011 6 425 http content 6 1 425 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Microstructure of non-polar GaN on LiGaO2 grown by plasma-assisted MBE 1 2 3 1 2 1 Cheng-Hung Shih Teng-Hsing Huang Ralf Schuber Yen-Liang Chen Liuwen Chang Ikai Lo Mitch MC Chou2 and Daniel M Schaadt3 Abstract We have investigated the structure of non-polar GaN both on the M - and A-plane grown on LiGaO2 by plasma-assisted molecular beam epitaxy. The epitaxial relationship and the microstructure of the GaN films are investigated by transmission electron microscopy TEM . The already reported epi-taxial relationship 1120 GaN 010 LGO and 1100 GaN 100 LGO for M -plane GaN is confirmed. The main defects are threading dislocations and stacking faults in both samples. For the M -plane sample the density of threading dislocations is around 1 X 1011 cm-2 and the stacking fault density amounts to approximately 2 X 105 cm-1. In the A-plane sample a threading dislocation density in the same order was found while the stacking fault density is much lower than in the M -plane sample. Introduction Gallium nitride GaN as one of the most important wide band semiconductors today has far-reaching applicability in electronic and optoelectronic devices. Its hexagonal crystal structure however exhibits a polar axis in the 0001 direction along which a polarization is present. The resulting polarization fields lead to intrinsically existent internal electric fields which give rise to a strong quantum-confined Stark effect when group III-nitride heterostructures are grown along the 0001 direction. As a consequence electrons and holes are spatially separated in such structures leading to a reduced wave function overlap and a decreased radiative transition energy. One way to circumvent these unwanted effects is to use non-polar surfaces of the hexagonal nitride structure such as the M -plane 1100 and A-plane 1120 for .