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%0 Thesis
%A Tuna, Öcal
%T Understanding and optimization of InN and high indium containing InGaN alloys by metal organic chemical vapor deposition
%C Aachen
%I Publikationsserver der RWTH Aachen University
%M RWTH-CONV-144505
%P III, 159 S. : Ill., graph. Darst.
%D 2013
%Z Aachen, Techn. Hochsch., Diss., 2013
%X Among the III-nitride semiconductors (Ga, Al, In) N, InN is the most attractive one due to having the narrowest bandgap of 0.64 eV. The revision in the bandgap of InN makes the InGaN more important since one can cover the whole solar spectrum by only changing In composition in an InGaN layer. The comparison of quality of InN and InGaN layers grown using a metal organic chemical vapor deposition (MOCVD) and a molecular beam epitaxy (MBE) methods indicate that growth with MOCVD is the more challenging, again due to the high dissociation temperature of NH3 relative to the low decomposition temperature of InN (560-570 oC). However, there is significant interest in developing an MOCVD process for InN and InGaN growth since MOCVD technology is the technology currently in use for commercial fabrication of group III nitride thin films. This thesis is therefore focused on a study of MOCVD growth of n- and p-type InN and In-rich InGaN films with the goal of providing new information on the influence of growth conditions on the film properties. Initially, a detailed investigation of MOCVD of InN is given. It is shown that MOCVD growth parameters (growth temperature and V/III ratio) have impacts on the layer properties such as In droplet formation on the surface as well as on its electrical and optical properties. PAS is employed for point defect analyzation. It is shown that In vacancies isolated by nitrogen vacancies are the dominant vacancy-type positron traps in InN. A decrease in the N vacancy concentration in InN is observed as a result of the growth temperature increase from 500 to 550 oC. This is an indication of a reduction of N vacancy concentration by enhancing NH3 dissociation at high growth temperature. Results obtained from optical techniques (Raman and PL) are used to estimate the free carrier concentrations in InN. Electrical characterizations are also carried out using Hall measurements. Carrier concentration values obtained by these three techniques revealed a similar trend in regard to the change of the V/III ratio. However, a huge difference with the carrier concentrations obtained by Hall and optical techniques is found. For the samples grown at a V/III ratio of 111k, a carrier concentration estimated by optical techniques is in the range of 9.0x1017 cm-3 compared to 6.0x1018 cm-3 found by Hall measurement. The huge difference in carrier concentrations obtained by the optical and Hall measurements is caused by parallel conductivity. The surface accumulation layer on InN and defects at the interface between InN/GaN dominates the Hall measurement results. Following InN, InxGa1-xN layers with various In content ranging from 40
%K MOCVD-Verfahren (SWD)
%K Gasphasenepitaxie (SWD)
%F PUB:(DE-HGF)11
%9 Dissertation / PhD Thesis
%U https://publications.rwth-aachen.de/record/229535