| Abstract [eng] |
This doctoral thesis presents a study of photoluminescence efficiency in wide-band-gap III-nitride semiconductors. The work is aimed at investigation of efficiency-limiting processes and causes of efficiency droop in AlGaN epilayers and multiple quantum wells. Also, light emission in BGaN epilayers, which are prospective in view of lattice matching in AlGaN-based heterostructures, is investigated. Three mechanisms are revealed to be important for the droop in AlGaN and the dependence of their influence on carrier localization is demonstrated. In particular, stimulated emission is pointed out as an origin of the observed efficiency droop for the first time, and indicators of the predominant droop mechanism are suggested. Photoluminescence efficiency and structural quality of BGaN layers with increasing boron content grown on different substrates are studied, phase separation is revealed, and band gap bowing parameter is estimated. |
