Silicon heavily-doped gallium nitride hetero-epitaxial material structure and stress control method

Abstract

The invention relates to a silicon heavily-doped gallium nitride hetero-epitaxial GaN SBD material and a stress control method. The silicon heavily-doped gallium nitride hetero-epitaxial GaN SBD material comprises a substrate; an aluminum nitride (AlN) nucleating layer; an unintentionally doped indium gallium nitride (InGaN) layer; an unintentionally doped gallium nitride (GaN) layer; an n < + >-GaN heavily doped layer; and an n <->-GaN lightly doped layer. Based on vapor phase epitaxial growth methods such as metal organic chemical vapor deposition (MOCVD), the unintentionally doped InGaN layer is introduced and stress modulation is carried out on the AlN nucleating layer, so the doping concentration of the n < + >-GaN heavily doped layer is remarkably improved while low stress and high quality of the epitaxial material are ensured, so that parasitic series resistance of high-frequency devices such as GaN Schottky diodes (SBD) is effectively reduced, and the cut-off frequency and theworking efficiency of the devices are improved. The method is compatible with a conventional GaN hetero-epitaxial process and is good in controllability.

Description

technical field [0001] The invention relates to a material structure and a stress control method of silicon heavily doped gallium nitride heterogeneous epitaxy, belonging to the technical field of semiconductor epitaxy materials. Background technique [0002] To realize the application of the terahertz frequency band, it is first necessary to develop a terahertz power source chip. At present, the main way to develop terahertz power source chips is SBD technology, etc., using the principle of SBD frequency multiplication to realize terahertz circuits above 300 GHz. Compared with gallium arsenide (GaAs), GaN materials have the characteristics of wide band gap, high breakdown and high electron saturation speed, so GaN high-frequency devices can obtain higher output power. However, due to the high parasitic series resistance of GaN SBD and other high-frequency devices developed at this stage, the cut-off frequency and working efficiency are low, resulting in device performance ...

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Problems solved by technology

Moreover, the thermal expansion coefficient of common substrates (silicon carbide, silicon, etc.) is lower than that of GaN, so the tensile stress of the wafer will further increase during the cooling process after epitaxy

When the tensile stress increases to a certain extent, a large number of cracks will appear on the surface of the epitaxial material, which will seriously affect the quality of the material.

In order to relieve the tensile stress of the disc, it is necessary to reduce n + -GaN re-doped layer doping concentration to reduce n + -The tensile stress increment during the growth of the GaN heavily doped layer, but it will cause high parasitic series resistance of high-frequency devices such as GaN SBD, which cannot meet the development requirements of terahertz power source chips

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