Separation of thick HVPE-GaN films from GaN templates using nanoporous GaN layers

Highlights

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The porous GaN layer enables a reduced stickiness between thick HVPE-GaN films and GaN templates.

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The preparation of nanoporous GaN consists 3 parts: the spin-coating of silica colloid, the GaN growth and HF etching.

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The 150–240 nm thick nanoporous GaN layer can serve as a sacrificial layer for self-separation of thick HVPE-GaN films.

Abstract

In this work, we have succeeded in growing an approximate 2-inch self-separated thick GaN wafer by hydride vapor phase epitaxy with an introduction of a sacrificial layer of nanoporous GaN. Such nanoporous GaN layer is invented by using the HVPE growth of thin GaN layer on the spin-coating silica nanosphere layer followed by a hydrofluoric acid etching to the silica nanosphere layer. It has been found that the nanoporous GaN layer, enabling a reduction of stickiness between thick GaN films and the substrates, plays a significant role in the self-separation of thick GaN films during the cooling process. However, the thickness of the nanoporous GaN layer is another key issue to achieve good quality self-separated GaN thick films. In our study, we suggest that the nanoporous GaN layer with a thickness of approximately 150–240 nm can best serve as the sacrificial layer in self-separation process. Raman spectroscopy also indicates the self-separated thick GaN films by using the proposed approach are virtually strain-free.

Keywords

Hydride vapor phase epitaxy,

Nanoporous GaN,

Silica colloid,

Spin-coating,

Self-separation,

GaN crystal,

Source:ScienceDirect

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