scholarly journals In-Situ Preparation of GaN Sacrificial Layers on Sapphire Substrate in MOVPE Reactor for Self-Separation of the Overgrown GaN Crystal

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1100
Author(s):  
Sepideh Faraji ◽  
Elke Meissner ◽  
Roland Weingärtner ◽  
Sven Besendörfer ◽  
Jochen Friedrich

GaN layers on sapphire substrates were prepared by using metal organic vapor phase epitaxy (MOVPE) combined with an in-situ H2 etching process for the purpose of later self-separation of thick GaN crystals produced by hydride vapor phase epitaxy (HVPE) on such substrates. The etching process results in deep pits and long voids that formed on the surface and along the lower interface between GaN and sapphire, respectively. The pits, which were investigated by SEM analysis, can be modified in their aspect ratio and density by controlling the etching parameters. Using a proper set of in-situ etching parameters, a seed layer with internal voids can be prepared, which is suitable for HVPE overgrowth and the self-separation process. The quality of the in-situ-etched seed GaN layer and overgrown GaN crystal were characterized by X-ray diffraction (XRD) and defect selective etching (DSE). With the aid of atomic force microscopy (AFM) in tapping mode, the interface morphology of the separated GaN crystal was analyzed. The crystal quality of the separated HVPE-GaN crystal is comparable to the crystal grown on untreated GaN MOVPE-seed, which did not separate from the sapphire substrate. The introduced technique to promote the crystal separation during the HVPE process has no obvious drawback on the quality of the grown GaN crystals. Using this technique, the self-separation occurs more gently due to a weakened interface between GaN/sapphire. The conventional separation from an untreated seed by pure thermomechanical action results in higher mechanical forces on the crystal and consequently much higher risk of crystal breakage.

CrystEngComm ◽  
2016 ◽  
Vol 18 (40) ◽  
pp. 7690-7695
Author(s):  
Seohwi Woo ◽  
Sangil Lee ◽  
Uiho Choi ◽  
Hyunjae Lee ◽  
Minho Kim ◽  
...  

A 2 in.-diameter free-standing m-plane GaN wafer was fabricated through in situ self-separation from m-plane sapphire using HCl chemical reaction etching (HCRE) in hydride vapor-phase epitaxy (HVPE).


2009 ◽  
Vol 404 (23-24) ◽  
pp. 4919-4921
Author(s):  
Anatolij Govorkov ◽  
Alexsandr Donskov ◽  
Lev Diakonov ◽  
Yulia Kozlova ◽  
Sergej Malahov ◽  
...  

1997 ◽  
Vol 482 ◽  
Author(s):  
A. Usui

AbstractA new approach to grow thick GaN layers by hydride vapor phase epitaxy (HVPE) is described. Selective growth is carried out at the beginning of growth. The coalescence of selectively grown facet structures makes it possible to achieve a flat surface over the entire substrate. As a result, crack-free GaN films with mirror-like surfaces are successfully grown even to a thickness of about 100 μm on a 2-inch-diameter sapphire substrate. The extended defect density is as low as 6×107 cm−2. The reduction mechanism for dislocation is discussed based on TEM observation. The high optical properties of FIELO GaN are confirmed by 5 K photoluminescence and reflectance measurements.


2014 ◽  
Vol 403 ◽  
pp. 38-42 ◽  
Author(s):  
Koji Koyama ◽  
Hideo Aida ◽  
Seong-Woo Kim ◽  
Kenjiro Ikejiri ◽  
Toshiro Doi ◽  
...  

2007 ◽  
Vol 102 (12) ◽  
pp. 123507 ◽  
Author(s):  
T. Paskova ◽  
L. Becker ◽  
T. Böttcher ◽  
D. Hommel ◽  
P. P. Paskov ◽  
...  

2016 ◽  
Vol 9 (4) ◽  
pp. 045501 ◽  
Author(s):  
Xue-Hua Liu ◽  
Ji-Cai Zhang ◽  
Xu-Jun Su ◽  
Jun Huang ◽  
Shu-Nan Zheng ◽  
...  

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