GaN SUBSTRATE

摘要

PROBLEM TO BE SOLVED: To provide a GaN single crystal substrate in which surface level difference is suppressed such that the epitaxial layer level difference becomes 0.5μm or less. SOLUTION: Polishing is performed using abrasive grains having a constant ejection. Abrasive grains having a constant ejection do not enter a defect collective region H strongly to recess a stripe core H. Since the defect collective region H is weak to strong alkali, solution of weak alkali (e.g. NH4OH) is employed. Height of the recess in the stripe core is controlled to 0.5μm or less, 0.2μm or less, or 0.03μm or less by two ideas. When the upper limit of the allowable level difference of an epitaxial layer is 0.5μm and the width of the stripe core is D (μm), level difference Q (μm) of the substrate is set Q≤10/D. Consequently, (1) the stripe H has chemical and physical properties different from those of the surrounding Ga surface, (2) when polishing is performed under same conditions, the stripe core H becomes a recess and the GaN crystal has a low part of the stripe core H and other high part, and (3) a problem that a level difference appears in the epitaxial layer being grown on such a substrate is solved. COPYRIGHT: (C)2005,JPO&NCIPI