The Growth Mechanism of GaN V-defect and Novel Method for GaN Epilayer Transfer

• Main Authors: PeiYen Lin, 林沛彥
• Other Authors: YewChung Sermon Wu
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/55113576717688067712

碩士 === 國立交通大學 === 材料科學與工程系 === 90 === This thesis investigates and discusses the formation mechanism of V-defect on GaN epilayer based on the appearance of large V-defect. Although facets and crystal shape of large V-defect and dot patternd GaN ELOG are similar, they are not the same from the thermodynamic and kinetic point of view based on calculated total free energy. V-defect is a result of an unstable energy of state so the appearance of V-defect is mostly likely resulted from the kinetic control during epitaxy process. The discussion of the formation of V-defect is divided into two parts: nucleation and growth. Nucleation step is related to the change of polarity of certain area on GaN epitaxy film; growth step is influenced by the different growth rate of different facets. Change in polarity on epitaxy film is due to the defect that is generated during the deposition of epitaxy film. The polarity of a certain area changes the growth rate of that specific area and thus nucleates a V-defect. After nucleation, V-defect turns into growth up or elimination depend on comparing of (0001) and facets of GaN which affected by different growth conditions. By previous research, the facets growth rate may change by varying temperature, pressure, V/III ratio, and dopant. We suppose upper factors are associate with Ga diffuse and bonding abilities. Better Ga diffuse ability and lower bonding probability may cause facet growth faster. The “nucleation and grwoth” model can reasonable explain both previous experience evidences without any exception and the formation of large V-defect. This thesis also introduces a novel GaN epilayer transfer method. This method combines ELOG GaN, wafer bonding technology, and selective wet etching to acheieve the purpose of integration a high quality GaN film on a selective substrate. By preliminary evaluation, the novel method has many advantages and worth to advanced research.