The characterizations of superlattices and delta-doped epi-layers grown by atmospheric pressure metalorganic chemical vapor deposition (MOCVD) have been investigated. As an basic study, the electrical properties of n-$Al_xGa_{1-x}AS$ (00.2) due to deep DX center have been investigated. The anomalous conduction band density of states which can be found in the course of the anayses of the Hall-effect measurement results, has been confirmed. Moreover, the physical origin for this anomaly was also discussed.
On the basis of this basic study, the growth technology of GaAs/AlGaAs superlattices and modulation doped heterostructures has been studied. By the proper undestandings of flow pattern during growth and design parameters of a reactor, it was proven using photoluminescence, double crystal x-ray diffraction, Hall-effect, C-V profiling and quantum-Hall effect measurements, that the successful growth of these novel structures was possible by MOCVD.
The growth technology has been extended to the study of delta-doping which is arised as a novel doping technique and is mainly done by MBE. Although the growth temperatures for delta-doped layer by MOCVD is as higher as 150°C than those of MBE, it was found utilizing C-V profiling, Hall-effect and Shubnikov de Haas (SdH) measurements, that the excellent delta-doping profiles were resulted. This excellent result implies and additional diffusion limiting mechanism which is absent in MBE growth. One possible model for this mechanism is suggested. In addition, a perliminary delta-FET has been fabricated to see the feasibility of the application.
The GaAs-on-Si technology which has been drawn much attentions due to its commercial utility has been studied. To reduce the dislocation density, in GaAs epi-layer, generated from GaAs/Si hetero-interface due to lattice and thermal mismatches, the annealing experiment employing a pulsed ruby laser (pulse duration time-25nS) has been performed. The formation of a stress-released. The formation of a stress-released GaAs layer on the laser-annealed surface during laser melting and regrowth process has been found. Furthermore, the high crystalline quality of he stress-released layer is detected by Raman, double crystal x-ray diffraction, etch pit density measurements. In addition, when a epi-layer is regrown on the stress-released layer, the stress-released layer is proven to have a role of preventing the dislocation-penetration into the regrown epi-layer.
For the first time, a delta-doped GAAs layer grown on Silicon substrate has been demonstrated. This may be promising since it couples the GaAs-on-Si technology and the delta-doping technology. It was found that the delta-doping profile was strongly influenced by buffer layer thickness. This implies that the doping profile is controlled by the environmental dislocation density. Thus this result can be explained by a dislocation-accelerated diffusion of impurity. However, the nearly ideal delta-doping profile can be obtained as far as thick buffer layer (>3μm) is introduced. Therefore, the applicability to the realization of delta FET-on Si has been established.
최근 화합물 반도체 에피층 성장장치로 크게 각광받고 있는 MOCVD 에 의하여 GaAs/AlGaAs 초격자 및 delta doping 한 에피층을 성장하여 그 특성을 조사하였다.
먼저 기본적인 연구로 Si 를 도핑한 n-$Al_xGa_{1-x}As$ (0
