GaN Growth by Nitrogen ECR-CVD Method
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3 Center for Condensed Matter Sciences, National Taiwan University, Taiwan. 4 Department of Physics, Fu-Jen University, Taiwan. 5 Tar-Tong Institute of Technology, Taipei, Taiwan 6 Department of Physics, National Taiwan University, Taiwan. ABSTRACT A new approach toward GaN growth using electron cyclotron resonance assisted microwave plasma enhanced chemical vapor deposition (ECR-CVD) method has been implemented. This growth technique allows for low- as well as high-temperature deposition, the use of pure nitrogen source, and a wide operating pressure that is between MOCVD and MOMBE. The unique features of this technique enable the growth of the epitaxial layer of GaN on a variety of substrates including sapphire, silicon, and LiGaO2. SEM, XRD, Raman, photoluminescence (PL), and Hall measurement are employed to characterize the deposited films. Highly oriented, (0001) textured films in the expected wurtzite structure with blue emission have been obtained. INTRODUCTION The growth and applications of III-Nitride materials has been the focus of many institutes in the field of optoelectronics in the past few years.[1-5] The blue lightemitting materials, such as GaN and AIN, are of high potential toward high intensity LED, laser diode, and high speed, high temperature electronic device.[6] Therefore, tremendous efforts have been applied to the epitaxial growth and doping of III-Nitride materials. Most of the work so far can be divided into two categories: the MOCVD method[7,8] and the low pressure MOMBE method.[9,10] The MOCVD method uses thermal excitation to generate nitrogen atoms from NH 3 precursor. In such a process, high temperature and high NH 3 flux are needed in order to produce enough reaction species at a pressure range between Torrs to atmospheric pressure. However, the choice of substrate material is restricted by the high temperature and the large amount of hydrogen during MOCVD process. In contrast, the MOMBE method requires UHV system and allows lower temperature deposition. [9,10] Despite that the MOMBE method offers some apparent advantage over the MOCVD method, the optical property of the film deposited by the MOMBE method is still unsatisfactory. While high performance film can be obtained by the MOCVD method, the quality of the film is yet inferior compared with most other heteroepitaxial semiconductor systems. Hence, not only there are rooms for further improvement of the film quality but also it remains to be a great challenge to develop novel technique for the growth of high quality III-Nitride materials. In this work, we present a new approach to the growth of III-Nitride materials by using electron cyclotron resonance (ECR) assisted microwave plasma enhanced CVD method. For brevity, ECR-CVD is used hereafter for the process in the present report. The ECR-CVD process is operated in a pressure range between those for the MOMBE and the MOCVD methods. Furthermore, since the nitrogen atoms and ions are generated
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Mat. Res. Soc. Symp. Proc. Vol. 423 01996 Materials Research Society
by ECR and
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