High-quality Ga-rich AlGaN grown on trapezoidal patterned GaN template using super-short period AlN/GaN superlattices for rapid coalescence

Highlights

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AlN/GaN SLs improves the lateral to vertical growth rate ratio up to 4.79 for Al26.1Ga73.9N.

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The growth rate of GaN decides the lateral to vertical growth rate ratio of AlN/GaN SLs.

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Trapezoidal patterned GaN template suppressed crack formation in overgrown AlGaN layers.

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Trapezoidal patterned GaN template reduces mismatch dislocations in overgrown AlGaN layers.

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Trapezoidal patterned GaN template reduced dislocation density from 2×109 cm−2 to 2×108 cm−2.

Abstract

High quality crack-free Ga-rich Al26.1Ga73.9N film was grown on trapezoidal patterned GaN template (TPGT) by low-pressure metalorganic chemical vapor deposition. The super-short period AlN/GaN superlattices structure was used to grow AlGaN material instead of the direct growth method. We obtained large lateral to vertical growth rate ratio larger than 4.79. The growth rate of GaN layer was proved to be the decisive factor of the lateral to vertical growth rate ratio. Moreover, for AlGaN growth, we found that that the TPGT is more beneficial to suppression of crack and relaxation of biaxial tensile strain than planar GaN template. The obtained results demonstrate that, comparing with AlGaN grown on planar GaN template, the threading dislocation density in AlGaN grown on TPGT was reduced from 2×109 cm−2 to 2×108 cm−2.

           Keywords

A1. Defect,

A3. Selective epitaxy,

A3. Metalorganic chemical vapor deposition,

A3. Superlattices,

B2. Semiconducting III-V materials

Source:PHYS

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