<title>GaAs compliant substrates: a new substrate with a stretchable lattice for mismatched III-V epitaxial growth</title>

Abstract

We present the theoretical foundations and implementation methods for forming GaAs compliant substrates that have a 'stretchable' lattice to be used for high quality lattice- mismatched heteroepitaxial growth. The theoretical calculations predict an increase of several orders of magnitude in the critical thickness of a film when it is grown on another thin film that has been wafer-bonded to an angularly misaligned bulk substrate. The calculations show that the increase in critical thickness is sustained even for a 3 percent lattice mismatch between the growth and the stretchable lattice. The dependence of the growth's critical thickness on a variety of parameters are presented including the bonding energy between the compliant and bulk substrates, the lattice mismatch between the growth and compliant substrates, and the thickness of the misaligned film. Thick films of In<SUB>0.35</SUB>Ga<SUB>0.65</SUB>P were grown on the compliant substrates. Bright-field transmission electron micrographs of the growth's cross-section showed no dislocations, whereas the same films grown on bare GaAs substrates produced stacking faults and threading dislocations. The concept and technology of compliant substrates may have important applications in forming optoelectronic devices of new characteristics and wavelengths.