Seed and seedholder combinations for high quality growth of large silicon carbide single crystals

Abstract

A silicon carbide seeded sublimation growth system and associated method are disclosed. The system includes a crucible, a silicon carbide source composition in the crucible, a seed holder in the crucible, a silicon carbide seed crystal on the seed holder, means for creating a major thermal gradient in the crucible that defines a major growth direction between the source composition and the seed crystal for encouraging vapor transport between the source composition and the seed crystal, and the seed crystal being positioned on the seed holder with the macroscopic growth surface of the seed crystal forming an angle of between about 70 DEG and 89.5 DEG degrees relative to the major thermal gradient and the major growth direction and with the crystallographic orientation of the seed crystal having the c-axis of the crystal forming an angle with the major thermal gradient of between about 0 DEG and 2 DEG .A silicon carbide seeded sublimation method is disclosed. The method includes the steps of nucleating growth on a seed crystal growth face that is between about 1 DEG and 10 DEG off-axis from the (0001) plane of the seed crystal while establishing a thermal gradient between the seed crystal and a source composition that is substantially perpendicular to the basal plane of the off-axis crystal.

Description

Background of the invention

[0001] The present invention relates to the sublimation growth of large single polytype crystals of silicon carbide.

[0002] Silicon carbide (SiC) has been known for many years to have excellent physical and electronic properties that theoretically allow fabrication at higher temperatures, higher power and higher frequencies than devices made from silicon or gallium arsenide Electronic devices that work under. About 4×10 6 High breakdown electric field of V / cm, about 2.0×10 7 The high saturation electron drift velocity of cm / s and the high thermal conductivity of about 4.9 W / cm-K make SiC conceptually suitable for high-frequency, high-power applications.

[0003] Especially compared with other semiconductor materials, silicon carbide also has a very wide bandgap (for example, the bandgap of α-SiC is 3 electron volts (eV) at 300K, compared with 1.12eV and 1.12eV of Si). GaAs has a band gap of 1.42eV), has high electron mobility, is physically ve...

Images