(110) Si wafer에서 Fe 도핑된 GaN HEMTs의 특징

Abstract

최근 III-V족 화합물 전력 반도체 시장에서 기존의 반도체를 넘어선 새로운 물성 및 전기적, 광학적 특성을 가진 반도체가 부각되고 있다. 이에 따라 몇 년 전부터 이 분야에 대한 연구가 활발히 이루어졌으며, 집중적으로 연구되고 있는 분야인 GaAs, InAs 이외에 새롭게 GaN을 이용한 연구로 그 영역을 넓혀가려 한다. 본 논문은 GaN 전자소자의 와이드 밴드갭(Eg=3.4eV)과 고온 안정성 등 재료적 특징으로 인하여 고출력 RF 전력증폭기와 고 전력용 전력반도체 응용에 큰 장점을 가지는 기초 연구인 기판 성장에 주 목적을 두었다. Si CMOS를 같은 기판에 집적화하면서 동시에 GaN 소자의 특징을 활용하는 이점을 가진 Si(110) wafer를 사용하여 Molcular Beam Epitaxy(MBE) 장비로 800℃ 정도의 상대적으로 낮은 온도에서 (MOCVD 의 경우 1100℃ 이상) GaN을 성장시켰으며, GaN와 Si 이종물질 간의 결합 시 발생되는 격자함수 차이와 열팽창 계수에 의해 발생하는 표면 crack을 제거하기 위해 스트레스를 이완하는 buffer layer를 각 여러 가지 형태로 넣어 crack-free한 표면을 갖는 GaN을 성장시킬 수 있었다. 그리고 기존 MBE 성장의 단점인 성장 속도를 극복하기 위한 방안으로 NH3 분위기에서 질소 원자를 rich 하게 하여 성장시켰으며, 버퍼의 절연 특성을 개선하기 위하여 Fe 도핑의 최적 조건을 연구하였다. 제작된 소자의 항복전압 및 누설전류 특성을 분석하기 위하여 측정온도를 변화시키면서 버퍼의 구조에 따른 특성 변화를 관찰함으로서 가장 효율적인 구조를 연구하였다.| Recently in III-V Group Compound semiconductor market, new semiconductors containing improved characteristics in physical, electrical, and optical aspects have risen in prominence. In turn, this field has been intensively studied for the past couple of years, and there is a series of new effort to use GaN on top of the established GaAs and InAs methods. This paper will cover substrate growth research which is advantageous in high power RF power amplifier and high power semiconductors, focusing on parts due to GaN electron particles’ wide bandgap (Eg=3.4eV), stability at high temperatures, and material characteristics. Integrating Si CMOS substrates and utilizing Si(110) wafers which have GaN device advantages, allowing growth of GaN at relatively low temperatures of 800℃ (over 1100℃ in case of MOCVD) by using Molecular Beam Epitaxy (MBE) equipment, GaN can be grown crack-free by using buffer layers in different forms to relieve the stress on the GaN and Si heteromaterial combination cracks due to lattice function difference and the heat expansion coefficient. In order to overcome slower traditional MBE growth rates, an NH3 environment rich in nitrogen molecules was used, and the optimal Fe doping conditions were researched in order to improve the insulating characteristics of the buffer layer. To analyze the breakdown voltage and leakage current of the device, the temperature was varied to observe the characteristic change in the buffer layer structure so that the most efficient structure may be discovered.; Recently in III-V Group Compound semiconductor market, new semiconductors containing improved characteristics in physical, electrical, and optical aspects have risen in prominence. In turn, this field has been intensively studied for the past couple of years, and there is a series of new effort to use GaN on top of the established GaAs and InAs methods. This paper will cover substrate growth research which is advantageous in high power RF power amplifier and high power semiconductors, focusing on parts due to GaN electron particles’ wide bandgap (Eg=3.4eV), stability at high temperatures, and material characteristics. Integrating Si CMOS substrates and utilizing Si(110) wafers which have GaN device advantages, allowing growth of GaN at relatively low temperatures of 800℃ (over 1100℃ in case of MOCVD) by using Molecular Beam Epitaxy (MBE) equipment, GaN can be grown crack-free by using buffer layers in different forms to relieve the stress on the GaN and Si heteromaterial combination cracks due to lattice function difference and the heat expansion coefficient. In order to overcome slower traditional MBE growth rates, an NH3 environment rich in nitrogen molecules was used, and the optimal Fe doping conditions were researched in order to improve the insulating characteristics of the buffer layer. To analyze the breakdown voltage and leakage current of the device, the temperature was varied to observe the characteristic change in the buffer layer structure so that the most efficient structure may be discovered.