Gallium Nitride (GaN) Templates

In the field of nitride semiconductors, a “GaN template” refers to a composite substrate which includes a thin layer of GaN or AlN deposited epitaxially on a foreign substrate such as sapphire, silicon or silicon carbide. The thickness of the nitride layer is usually between 1 and 250 microns. Kyma’s GaN templates are built on sapphire as well as silicon substrates and are available in 2”, 3”, and 100mm diameter. They exhibit industry leading low defect densities and are epi ready with low surface roughness.

Kyma GaN templates grown by HVPE provide a higher purity GaN buffer for subsequent device epitaxy. Typical customer benefits include:

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Elimination of long (2-5um) MOCVD or MBE undoped buffer growth
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HVPE based GaN epitaxy has higher purity and transparency than MOCVD based GaN epitaxy
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In high volume, HVPE based templates will have:
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Significantly lower growth time/cost vs MOCVD templates due to the much higher growth rates possible with HVPE
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Lower raw material costs as metalorganic gallium sources are replaced with metal gallium and ammonia usage is 1/10th that of MOCVD

Specification Sheet Characterization Methods

Characterization of gallium nitride wafers as shown in our specification sheets is completed using the following methods:

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Wafer thickness, Bow and TTV are determined by a Sigmatech thickness mapper for round substrates. Square substrates are measured manually at predetermined points on the wafers.
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Wafer orientation is determined by x-ray diffraction
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Conductivity is determined by Lehighton (n-type, semi-insulating) and/or Corema measurements (semi-insulating) and/or Hall measurements for our boule recipes, but are not made on all wafers shipped.
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Dislocation density is determined via etch pit density measurements followed by AFM and/or micro-cathodoluminescence (Micro-CL), but are not made on all wafers shipped.
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Macro defects are on the surface of the wafer and are counted by visual inspection.
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Surface roughness information is determined by atomic force microscopy (AFM) for the front surface finish. The typical image size for the measurement is 20x20µm.
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Epitaxial Film thickness for films under 5um thick is determined via Filmetrix or Wyko white light interferometers. Film thickness for films above 5um is typically determined by weight.