Title Netiesiatarpių puslaidininkių TlGaSe2 ir SiC fotoelektrinių ir optinių savybių tyrimas /
Translation of Title Photoelectrical and optical properties of indirect bandgap semiconductors TlGaSe2 and SiC.
Authors Gulbinas, Karolis
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Pages 41
Keywords [eng] layered semiconductors ; photoacoustic responce ; TlGaSe2 ; SiC
Abstract [eng] Growing interest and needs of modern semiconductor engineering require development of new materials offering new prospects. In this study we investigate wide bandgap semiconductors: two dimensional layered TlGaSe2 and few polytypes of SiC, namely, 6H, 4H and 3C. The goal was to obtain new knowledge about optical properties, structure and charge transport mechanisms in these materials. Photoacoustic response and free carrier absorption techniques were applied for bandgap absorption study in TlGaSe2.in parallel and in perpendicular directions to the layer plane. Optical anisotropy was revealed related to structural phase. Bandgap photoluminescence at room temperature in TlGaSe2 was detected and its origin was explained. In fluorescing 6H-SiC heavily co-doped with N-donors and B-acceptors layer wide optical and photoelectrical studies were performed to understand carrier transport and recombination mechanisms dependent on doping conditions. Low diffusion coefficient and weak surface recombination were determined. Two types of boron states determine millisecond carrier lifetimes. The photoluminescence spectrum is composed of two overlapping peak bands. In thin 4H-SiC epilayers surface passivation influence to epilayer carrier lifetime was investigated to determine the best passivation conditions using Al2O3 and SiO2 oxides and its resistivity to radiation. In free standing 3C-SiC epilayer detached from undulant Si substrate, the in-depth analysis was performed for the residual stress effects on carrier lifetime and bandgap absorption.
Dissertation Institution Vilniaus universitetas.
Type Summaries of doctoral thesis
Language Lithuanian
Publication date 2015