원자력연구소의 전문인력의 도움을 받아 원자로에서 나오는 열중성자(thermal neutron)를 GaN epilayr와 ZnO, GaN, Si 나노선에 조사(iradiation)하여 각각의 나노선 내에 새로운 불순물 준위(defect level)을 형성한 후, 이들 준위에 의한 ZnO 반도체의 광학적 특성의 변화를 측정한다. 또한 중성자가 조사된 시료와 thermal anneling한 시료를 비교 분석하여 중성자의 조사에 의한 불순물 준위의 형성기원과 과정을 규명하고, 중성자 조사에 의한 ZnO, GaN, Si나노선 반도체의 ann
원자력연구소의 전문인력의 도움을 받아 원자로에서 나오는 열중성자(thermal neutron)를 GaN epilayr와 ZnO, GaN, Si 나노선에 조사(iradiation)하여 각각의 나노선 내에 새로운 불순물 준위(defect level)을 형성한 후, 이들 준위에 의한 ZnO 반도체의 광학적 특성의 변화를 측정한다. 또한 중성자가 조사된 시료와 thermal anneling한 시료를 비교 분석하여 중성자의 조사에 의한 불순물 준위의 형성기원과 과정을 규명하고, 중성자 조사에 의한 ZnO, GaN, Si나노선 반도체의 annealing 및 dopig 방법을 모색한다. 또한, ZnO, GaN, Si nanowire에 중성자를 조사하여 나노선에 미치는 영향에 대해서도 알아보았다. 이러한 결과를 이론적인 계산과 비교하였다.
Abstract▼
The potential applications for quantum devices would be represented with one- dimensional nanostructured materials. Recently, the trend leads to conveying wide-gap compounds semiconductor to nanowires for optoelectronic and nanoelectronic devices. but there are so many problems to make the electroni
The potential applications for quantum devices would be represented with one- dimensional nanostructured materials. Recently, the trend leads to conveying wide-gap compounds semiconductor to nanowires for optoelectronic and nanoelectronic devices. but there are so many problems to make the electronic devices or optical devices. The most important thing of the problems is how we dope in nano-materials. one of the methods to solve the problem is NTD. What is the NTD? When materials are irradiated by neutrons, impurities in the neutron-irradiated material are produced. This reaction has been utilized as a means of impurity doping and this is called the Neutron-Transmutation-Doping. Constituent isotopes in semiconducting materials, when they react with thermal neutrons, become other isotopes by obtaining n$^1$. Some unstable isotopes created by neutron irradiation are transmuted to other atoms after beta and gamma recoils. Impurities can be doped in semiconductor by these nuclear reactions. However, fast neutrons that neutron beams contain just damage semiconductor and give no nuclear reaction because of their very low cross section Neutron-irradiated semiconductors must be annealed to annihilate damages produced by fast neutrons and to remove unwanted effects induced by thermal neutrons. Annealing may move interstitial transmuted atoms to their original sites in lattices by supplying thermal energy. The NTD is advantageous to control the concentration of impurities and to dope impurities homogeneously into semiconducting materials. Compared with the conventional in-situ doping method, the concentration of transmuted impurities may be more accurately control led by neutron irradiation time and spatial dispersion of impurity distribution achieved by NTD is smaller by 10 times. This NTD method has been applied to a variety of semiconducting materials including Si, a-Si : H, Ge, GaAs, Inse, GaP, and GaS. For NTD-Inse, Sn atoms are transmuted from In. Recently, GaP has attracted considerable attention in the context of epilayers and heterostructures. In neutron-transmuted GaP, Ge and S impurities are transmuted from Ga and P atoms, respectively. And NTD-Si material has already been commercialized for high power devices. Impurities transmuted in Zno, GaN, Si nano-material after neutron irradiation are studied in this work. Transmuted atoms in nano-materials are identified on the basis of expected nuclear reactions and their concentrations are estimated, respectively. Transmuted impurities that are expected to be doped into nano-material are then confirmed by photoluminescence (PL) . However, there are differences between epilayer and nano-material in PL analysis. Our experimental results are expected to give deep impact on nano-material doping technaology for the achievement of the fabrication of nano-devices.
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