UV Responsivity Enhancement of A-axial GaN Nanowire via Piezophototronic Effect

  • 蔡 承祐

Student thesis: Master's Thesis


For the first time an ultrahigh UV responsivity of 105 (A/W) is demonstrated on a non-polar a-axial GaN nanowire metal-semiconductor-metal (MSM) UV photodetector incorporating piezophototronic effect It was observed that the UV responsivity of an a-axial GaN nanowire based MSM photodetector enhanced by a significant 180% from 5×104 to 1 3×105 (A/W) when a 0 012% tensile strain was applied on the nanowire Moreover the measured UV responsivity and output current enhances to a maximum at an optimum applied strain and then falls off The non-linearity enhancement in UV responsivity with applied strain is attributed to the competition between Schottky barrier height (SBH) effect and carrier trapping effect acting on carrier transport mechanisms induced by the unique piezopotential distribution in a strained a-axial GaN nanowire By further comparing devices having different estimated carrier concentrations we discovered that the maximum UV responsivity and output current shifted to higher tensile strain states as increasing carrier concentration The phenomenon is attributed to the difference in carrier screening effect on the strain induced SBH lowering effect and carrier trapping effect in terms of magnitude The results from this research suggest an optimum amount of strain should be applied on future a-axial GaN nanowire based MSM type sensors for best performance enhancement
Date of Award2015 Aug 13
Original languageEnglish
SupervisorChuan-Pu Liu (Supervisor)

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