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For solar-blind UV detector high Al composition n-type AlGaN growth

Author: LiuCheng
Tutor: ChenChangQing
School: Huazhong University of Science and Technology
Course: Physical Electronics
Keywords: Metal organic chemical vapor deposition AlGaN N Type dopant Indium - doped silicon UV detector
CLC: TN304.055
Type: Master's thesis
Year: 2011
Downloads: 58
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Abstract


Using metal organic chemical vapor deposition (MOCVD) method , in a high quality aluminum nitrogen (AlN) , and aluminum nitride by the template / AlGaN superlattice (AlN / AlGaN SLs) , and by changing the [TMA / (TMa TMG)] the flow ratio , successfully obtained a high Al composition of different conductivity of the n-type AlGaN (AlGaN) thin film . And through the microscope , atomic force microscopy (AFM), X -ray diffraction (XRD), transmission spectroscopy , Raman spectroscopy , Hall test and capacitance - voltage (CV) and other testing methods, the n-type (Al) GaN material surface morphology, crystal quality , optical and electrical properties were evaluated. Experimental results show that , while maintaining the constant flow rate in the case TMA TEG flow can be reduced to obtain a high Al composition AlxGa1-xN (x gt; 0.4) material . However, due to the growing surface of the Al atoms is less than the mobility of Ga atoms , so that the same growth conditions , by reducing the flow of TEG , accompanied by increase of Al composition of AlGaN is the deterioration of the surface morphology . By the silane into the growth process can be obtained through the n-doped (Al) GaN film . n-(Al) GaN thin films doped with silane molar amount of the increase , and its mobility increases with silane first increased and then decreased. Meanwhile , the increase of silane also lead to n-(Al) GaN material lattice damage and reduce the size thereof . For n-type doped AlGaN material , the more specific the Si doping levels increased as the Al content and deepened. Thus, for implementation using the same amount of silane doped AlGaN material , the actual dopant concentration increased with the decrease of Al composition . Meanwhile , since the Al composition of the AlGaN lattice constant increase caused by the reduction of the lattice material so that electron collision probability with increasing mobility of the material also will show a downward trend . Finally , indium - Si (In-Si) doped preliminary results , In the AlGaN materials, the introduction of the system can be improved to some extent AlGaN material quality of the surface morphology and crystal . Overall, this paper get high Al composition n-type AlGaN material can fully satisfy the solar-blind UV detector needs. Its analysis on the characteristics of AlGaN doped be used to guide the subsequent experimental work.

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