서지주요정보
질화물 반도체 레이저 다이오드의 제작과 특성에 관한 연구 = Study on the characteristics of III-Nitride semiconductor laser diodes
서명 / 저자 질화물 반도체 레이저 다이오드의 제작과 특성에 관한 연구 = Study on the characteristics of III-Nitride semiconductor laser diodes / 양민.
저자명 양민 ; Yang, Min
발행사항 [대전 : 한국과학기술원, 2001].
Online Access 원문보기 원문인쇄

소장정보

등록번호

8012183

소장위치/청구기호

학술문화관(문화관) 보존서고

DPH 01013

SMS전송

도서상태

이용가능

대출가능

반납예정일

초록정보

This thesis presents studies on GaN based laser diode(LD) structures. The crystal quality of epitaxially grown layers were characterized by cathodoluminescence(CL) and Epitaxially Lateral Over Growth(ELOG) technique was introduced to improve the GaN crytallinity in selected experiments. In addition to conventional ridge type structures, investigation of novel device structures was carried out. Experimental results were presented in conjunction with theoretical calculations. The crystalline characterization of epitaxially grown LD structure was performed using CL. The CL characteristics of undoped GaN, Si-doped GaN, Mg-doped GaN, and multi quantum wells(MQW) have been studied to idetify the defect-related emission lines and the spatial distribution of emission lines. It has been shown that there are two main emission peaks at 2.8eV and 3.2eV in Mg-doped GaN. In CL images, the 2.8eV emission was distributed over the entire area except for localized regions where 3.2eV emission was detected. The 3.2eV emission is attributed to crystal defects within Mg-doped GaN layer and it could not be completely quenched out even in highly Mg-doped GaN samples. In the case of MQW structures, it has been confirmed that CL emissions were seriously affected by crystal defects within the film. $SiO_2$-removed ELOG substrates were characterized by double X-ray diffraction and CL measurements. $SiO_2$-removed ELOG substrates have been shown superior substrate qualities, in terms of crystallinity and crystal tilting, to those prepared by normal ELOG techniques. Thermal treatments were carried out to enhance the activation efficiency of Mg in p-GaN and p-AlGaN layers in laser diode structures. The activation temperature was varied in the range 750℃~1000℃, and the gas ambient constituted of either pure nitrogen or mixed gas of nitrogen and oxygen. P-type contact resistance was reduced to as low as $2.2×10^{-6} Ω-㎠$ using mixed gas for activation (3% oxygen) and p-electrode annealing (20% oxygen). By improving the p-contact resistance, the operating voltage of LD was reduced from 8.7V to 5.9V at an applied current of 100mA. For a better understanding of the GaN LD performances, several simulations were carried out on ridge-type LDs, tacking into account of the ridge geometry, internal losses, and Al composition and thickness of the electron blocking layer. The ridge geometry that consists of its width, length, and etched depth(the distance from active region) strongly effects the core device characteristics such as threshold currents, optical modes, differential quantum efficiencies, and far field patterns. In real device structures, the threshold current can be reduced by as much as 40% from 225mA to 135mA by refining the ridge dimension, as expected from theoretical calculations. Moreover, dependence of device characteristics on operating temperature indicate the hole carrier concentration in p-AlGaN layers within LD structure should be increased to prevent electron overflow into p-cladding layers. Selective growth was attempted for the first time to realize a buried ridge(SGBR) type LD based on a III-nitride semiconductor. In this novel structure, the laterally grown regions have better crystallinity than the vertically grown regions, as confirmed by CL measurements. It could be expected from electroluminescence images that the current path is well defined by the current blocking layers in SGBR LD structures. Even though lasing has not yet been realized as because insufficient structural optimization, CL and I-V characteristics are greatly improved. Using the advantages of lateral growth, we ahve also tried other novel structures that demonstrateed stimulated emission. The new approach utilized a patterned n-GaN grown over a Pendeo substrate. The I-L characteristics of LDs grown on patterned substrates were improved, compared to those grown on bare Pendeo substrates. This improvement is attributed to superior crystal quality on laterally overgrown region on the patterned substrate.

서지기타정보

서지기타정보
청구기호 {DPH 01013
형태사항 vi, 125 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Min Yang
지도교수의 한글표기 : 이용희
지도교수의 영문표기 : Yong-Hee Lee
수록잡지명 : "Journal of crystal growth". Formation and characteristics of inversion domain in GaN grown by hydride vapor phase epitaxy, 213, pp. 235-240 (2000 Jun.)
학위논문 학위논문(박사) - 한국과학기술원 : 물리학과,
서지주기 참고문헌 : p. 119-125
주제 질화물 반도체
레이저 다이오드
Laser Diode
III-Nitride
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