| Summary: | 碩士 === 國立交通大學 === 電子物理系所 === 104 === In this thesis, we use the home-made Two-Heater MOCVD reactor to grow p-type GaN thin film. We aim to investigate the effects of substrate temperature(Ts) and ceiling temperature(Tc) on the films quality. The electrical, structure and optical quality were analyzed by Hall measurement, Charge neutrality principle, X-ray diffraction and Photoluminescence measurement.
In the substrate temperature varied series, Two-Heater mode (T.H.) Tc is fixed at 1150oC and Ts was designed to decrease from 1000oC to 725oC compared with the Conventional mode (Conv.). We find that the resistivity can maintain 2.69Ω-cm until Ts=800oC and the dislocation density are always 1.5x smaller than Conv. samples. In the ceiling temperature varied series, Ts is fixed at 800oC and Tc is changed from 650oC to 1150oC. We found that density of compensating donor has near 50x decrease from 4.5x1018cm-3 to 1017cm-3 and the normalized intensity of yellow emission(2.2eV) has also decrease more than 1000x with higher Tc. Therefore, we speculate that the ceiling temperature can provide a high temperature zone in upper chamber for III-precursors to crack more efficiently, hence less carbon impurity will incorporate in films.
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