Uniqueness of hydride vapour phase epitaxy in optoelectronic device fabrication

Non-equilibrium techniques like MOVPE (metal organic vapour phase epitaxy) and MBE (molecular beam epitaxy) have gained momentum owing to their ability to grow layers of only a few nm thickness with good uniformity in thickness and composition and good reproducibility. These processes are known to be operating under diffusion or kinetically controlled conditions. The increasing complexity of the modern discrete and integrated optoelectronic devices puts demand not only on the thin basic quantum structures but also on the following: (i) realisation of thick layers; (ii) selective regrowth of thick semi-insulating current confinement layers (≈5 μm) in high speed device fabrication to minimise parasitics; (iii) flexible means to achieve selective regrowth of semi-insulating layers around both [110] and [110] directional mesas individually or simultaneously (cross mesas); such a demand will be felt more and more when the demand on integration is even more acute and (iv) selective regrowth of semi-insulating layers around parallelepiped and cylindrical mesas in the fabrication of VCSELs (vertical cavity surface emitting layers); the surrounding semi-insulating layers will be essential for current confinement, effective thermal dissipation and high speed operation. In this invited paper we intend to show that the above demands can be easily met with by hydride vapour phase epitaxy (HVPE). Yet another related technique chloride vapour phase epitaxy (Cl-VPE) also operates with the same essential principles as HVPE. Hence what is applicable to HVPE is also applicable to Cl-HVPE