Single-phase high-quality semipolar (10–13) AlN epilayers on m-plane (10–10) sapphire substrates

Abstract

Single-phase flat semipolar (10-13) AlN epilayers on m-plane (10-10) sapphire substrates grown by ammonia-free high-temperature metalorganic vapor phase epitaxy are firstly demonstrated. It is found that twins and basal-plane stacking faults are undetectable by X-ray diffraction and crosssectional characterization. An X-ray rocking curve (XRC) shows the full widths at half maximum (FWHM) of the (10-13) and the (0002) diffraction peaks from a ∼2.3 μm thick AlN film as narrow as 322 and 373 arcsec, respectively, indicating a high structural quality. Semipolar AlN epilayers hold great promise for high performance deep-ultraviolet (DUV) optoelectronic device applications.

Growth of Semi-Polar (101¯3) AlN Film on M-Plane Sapphire with High-Temperature Nitridation by HVPE

“…In contrast, the high temperature (>1200 °C) is beneficial to promote the coalescence of AlN grains, and thus improve the quality of AlN film [ 6 ]. Moreover, some research groups have obtained high-quality semi-polar AlN in the high-temperature region, ranging from 1200 to 1650 °C [ 8 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. Jo et al obtained smooth (11 2) AlN with a thickness of 2 μm by metal organic chemical vapor deposition (MOCVD) at 1500 °C [ 21 ].…”

“…Jo et al obtained smooth (11 2) AlN with a thickness of 2 μm by metal organic chemical vapor deposition (MOCVD) at 1500 °C [ 21 ]. Shen et al prepared the best quality semi-polar (10 3) AlN with NH 3 -free metalorganic vapor phase epitaxy (MOVPE) at a high temperature of 1650 °C [ 20 ]. Sapphire and SiC are suitable substrates for such high growth temperature [ 15 , 22 ].…”

Perspectives on UVC LED: Its Progress and Application

“…Zhou et al developed a patterned sapphire substrate with periodic inlays of SiO 2 , which effectively reduced interface dislocations and increased the EQE of their UVA LED by 26.1% compared with that of the traditionally patterned substrates [35]. In addition to optimizing the sapphire substrate and epitaxial technology, the selection of other new substrate materials, such as AlN self-supporting substrates, semi-polar surface substrates, is another potential route to the improvement of UV LED technology [36][37][38].…”

Effect of High-Temperature Nitridation and Buffer Layer on Semi-Polar (10–13) AlN Grown on Sapphire by HVPE

“…However, the strong spontaneous and piezoelectric polarization along c-axis will weaken the recombination of carriers in the quantum wells [4], which in turn decrease the luminescence efficiency of devices. The use of semi-polar substrates and epitaxial layers [5][6][7][8][9], such as (10)(11), (10)(11)(12) and (10-13) AlN, can effectively solve this problem since the polarization field is greatly weakened [10,11]. According to the energy band structure, other semi-polar plane, such as (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22), can produce a negative polarization field across multiple quantum wells used in optoelectronic devices, which can reduce the confinement of hole states and increase the carrier loss.…”

“…Semi-polar nitride films were generally grown on M-plane sapphire [5,6], silicon [7,8] and ZnO [13,14]. It is also reported that native semi-polar AlN substrate were used for homoepitaxial semi-polar AlN [15].…”