Structural characterization of Ⅲ-nitride based alloys, heterostructures, and quantum wells = Ⅲ-N 질화물 반도체 이종접합구조와 양자우물구조의 구조적 특성

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The III-Nitride semiconductor system of InN, GaN, AlN and their ternary alloys are of great technological importance due to their direct and wide bandgaps and their refractory properties. To produce the high brightness light emitting diodes (LEDs) and (LDs) using III-Nitrides, however, total defect density such as threading dislocations, stacking faults, inversion domain boundaries(IDBs), etc. should be reduced in GaN buffer layers. In this thesis, we have mainly studied the structural properties of III-Nitride alloy, heterostructures, and quantum wells using Transmission electron microscopy(TEM). The final purpose of this thesis is to correlate structural properties with optical properties using various characterization facilities for the optimized sample structures. In the chapter 3, we have studied the effect of TMGa flow rate in the GaN nucleation layer on the optical and structural quality of GaN overlayer. From low temperature PL measurements, a GaN overlayer grown on a nucleation layer with the TMGa flow rate of 80μmol/min shows the intense donor-acceptor pair transition peak at 3.27 eV and the weak yellow band emission at 2.2 eV, which are related with stacking faults and threading dislocations from TEM images, respectively. As the TMGa flow rate of GaN nucleation increases, the threading dislocation density rapidly decreases and stacking fault density increases in the GaN overlayers. Also, a total threading dislocation density at the optimum condition of the nucleation layer is the very low $1 × 10^8 cm^{-2}$, which is due to the interaction of stacking faults with the vertical threading dislocations and the bending of threading dislocations near the stacking faults. HRXRD results show that a high density of stacking faults is correlated with the compressive strain of a GaN overlayer at the growth temperature. In the chapter 4, we have investigated the growth of crack free $Al_xGa_{1-x}N$ layer with low dislocation density using $Al_xGa_{1-x}N/GaN$ het...
Lee, Jeong-Yongresearcher이정용researcher
한국과학기술원 : 재료공학과,
Issue Date
174576/325007 / 000985840

학위논문(박사) - 한국과학기술원 : 재료공학과, 2002.2, [ xix, 245 p. ]


InGaN; quantum well; TEM; GaN; defect; 결함; 양자우물; 광학적특성; 구조적특성; 투과전자현미경

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