혼합소스 HVPE 방법을 이용한 비형광체 백색 발광다이오드 제작에 관한 연구

Abstract

The white light emitting diodes (LEDs) of non-phosphor were fabricated by mixed-source HVPE. The LED structure was made of p-n junction with double heterostructure. For the growth of the LED structure, multi-sliding boat system was introduced to the mixed-source HVPE.

The double heterostructure of the non-phosphor white LED was composed of Te-doped AlGaN as n-cladding layer, AlGaN as active layer, Mg-doped AlGaN as p-cladding layer, and Mg-doped GaN as p-capping layer. Prior to growth of the double heterostructure, single layers which consist of the LED structure were grown by the mixed-source HVPE, respectively. The crystal quality and optical properties of the layers were characterized by XRD, CRI and EL measurements.

The Al composition of the AlGaN layers was controlled by variation of temperature of source zone. In case of the LED structure, the composition of Al was in control of 16%. The carrier concentrations of Te-doped AlGaN layer were controlled by change of Te atomic fractions in the mixed-source. For the LED structure, the carrier concentration of the Te-doped AlGaN cladding layer was controlled in the order of 5 × 10^(18) cm^(-3). The hole concentrations of Mg-doped AlGaN layer and Mg-GaN layer were controlled by Mg atomic fraction in the mixed-source. The hole concentration of the Mg-doped GaN was controlled in the order of 3 × 10^(17) cm^(-3).

The double heterostructure was grown consecutively by the mixed-source HVPE using the multi-sliding boat system. The characteristics of the LED were evaluated by I-V, CRI and electroluminescence. Even though the LED grown by the mixed-source HVPE need to be more improved in optical and electrical properties, it is worth to note that newly developed method of Ⅲ-Nitride semiconductor LED could be a candidate technology for the fabrication of low cost LEDs.