Studies Of The Growth Of InN And In-rich InAIN And The Fabrication Of InN-based Devices

With the rapid development of photo-electronic technology and communicationtechnology, nitride semiconductor materials have attracted more and more attentionover the past decades. The mature lighting technology based on GaN has beencommercialized today, but indium nitride (InN) is only be concerned in recent years.InN owns lots of excellent properties, such as low electron effective mass, highmobility, high saturation velocity, and narrow band gap. The band gap of InN is about0.7eV, this value is of much attractive since its corresponding emission wavelength islocated on the optical window of quartz optical fiber communication. The band gap ofInAlN alloy covers from the near infrared to the ultraviolet spectral range and can becontrolled by adjusting aluminum content in the ternary alloy. Such character offers away to design various band gap structures. This dissertation focuses on the growth ofInN and In-rich InAlN alloy materials, and the related devices based on InN andInAlN.InAlN alloy is grown on sapphire substrate by molecular beam epitaxy (MBE)technology; the influence of growth parameters to the alloy’s properties has beenresearched. The aluminum content in the alloy will be increased if the temperature ofaluminum source increases and the uniformity of the film will become worse whenaluminum content increases. Indium droplets will appear if the nitrogen gas flow isinsufficient and aluminum content increases with the increase of nitrogen gas flow,but when the nitrogen gas flow is enough, indium droplets disappears and aluminumcontent changes very small. Aluminum content also increases with the temperature ofsubstrate increasing. Phase separation will occur if the temperature of substrate is toolow. Meanwhile, high temperature leads to degeneration of surface morphology. Thealloy achieves best surface morphology, highest crystal quality and electron mobilityunder490degree centigrade.The relation between aluminum content and band gap is researched byphotoluminescence (PL). The peak position of PL is blue-shifted when the aluminumcontent increases. The bowing parameter calculated from this relation coordinates tothe results of other papers.Three different devices are fabricated on p-GaN/sapphire substrate, GaN/InN,GaN/InN/InAlN and GaN/InAlN, respectively. The InN and InAlN grown on GaN/sapphire substrate owes much better surface morphology, electrical propertiesand crystal quality than on sapphire. near-infrared emission is observed from the InNside under forward bias and the EL emission peak is about1530nm. GaN/InN/InAlNstructure can increase the EL efficiency compared to GaN/InN structure. The EL ofInAlN is achieved successfully. The EL emission peak is about1032nm and thealuminum content is about15.8%, the arising of aluminum content can indeed enlargethe band gap of the alloy.