Gallium Nitride (GaN) Substrates
Semiconductor epitaxy is best performed on native substrates in order to minimize interface effects and defect formation. Gallium nitride epitaxy on Kyma GaN substrates greatly improves a number of important device properties of subsequent GaN epitaxy when compared with heteroepitaxial GaN on SiC, sapphire, or silicon. The benefits in lattice constant mismatch, dislocation density and thermal conductivity can be seen in the table below.
| Bulk GaN vs Non-native Substrates† |
| GaN on Bulk GaN | GaN on SiC | GaN on sapphire | GaN on Silicon |
| Lattice Constant Mismatch |
0% |
3.5% mismatch |
14% mismatch |
17% mismatch |
| Dislocation Density |
104 - 106 / cm2 |
1 x 109 / cm2 |
5 x 109 / cm2 |
1 x 1011 / cm2 |
| Thermal Conductivity |
2.5 W/cm-K |
1.3 W/cm-K |
1.2 W/cm-K |
1.0 W/cm-K |
|
| †This table is for statistical reference only and does not necessarily represent available Kyma Products |
Kyma's high purity GaN substrate allows GaN-based device manufacturers to eliminate interlayers, processing steps, and improve device quality over those grown on any other substrate. Detailed product descriptions and specification sheets are listed below.
All substrates have a typical dislocation density of 5x106 and epi-ready surface finish of <0.5 nm
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 20x20 microns.
Kyma Terms and Conditions
