| Abstract [eng] |
The work is divided into two parts where the growth of different group-III nitride semiconductors was investigated, targeting the fabrication of different heterostructure devices. The first part is dedicated to the growth and characterization of AlGaN and GaN with different polarities. The second part is dedicated to the growth, characterization and device application of the InN, a narrow band gap nitride semiconductor. Thus the main task of the work was to develop the MOVPE growth method for different III-group nitride semiconductor heterostructures with a potential for photonic, optoelectronic and photovoltaic devices in specific spectral ranges. The first part of the work presents AlGaN/GaN waveguide structure which can be used for the second harmonic generation. The novelty of this part is the inversion of GaN polarity on the AlGaN optical cladding layer. As calculation results showed, such double polarity GaN waveguide increases second harmonic generation efficiency. The inversion of the GaN polarity is achieved by inserting Al2O3, deposited by atomical layer deposition, between Ga-polarity and N-polarity GaN. After the deposition of the Al2O3 and nitridation/annealing processes, extensive N-polarity GaN growth experiments were performed in order to achieve a smooth N-polarity GaN surface. The second part of the work is dedicated to the growth of InN layers using the novel pulsed MOVPE technique. Implementing this growth technique, InN exhibits one wurtzite crystalline phase, which can be improved by growing it on the p-type GaN layers. Improvement in the crystalline quality let to achieve better electrical parameters. After the growth experiments of InN on the p-type GaN layer, photovoltaic response and external quantum efficiency measurements were taken. In the last part, InN/p-type GaN heterojunction modeling was performed. |
