Molecular-beam epitaxy of InN
Using single crystalline InN films obtained by MBE and MOVPE, studies using photoluminescence (PL) and optical absorption have been performed. The fundamental band gap of single crystalline InN was argued to be around 0.8 eV [1.61.11] instead of 1.9 eV which was determined from polycrystalline InN. Now, a narrow band gap of around 0.65 eV is widely recognized after several years of discussion. This new finding expanded the field of applications of group III nitrides, with the alloy systems spanning from 6.2 eV of AlN to 0.65 eV of InN. However, many scientific and technical issues hinder applications of InN-based material systems to actual devices. These include very high concentrations of residual donors, high densities of dislocations due to large lattice mismatch, surface accumulation of carriers, p-type doping and formation of high-quality heterointerface. To overcome these critical issues, further developments in MBE growth of InN-based materials are strongly required. In this chapter, we will review comprehensive studies of MBE growth of InN and related alloys.