GaN nanobelts are synthesized using the chemical vapor deposition method with the catalyst of Ni. The mi- crostrueture, composition and photoluminescence property are characterized by x-ray diffraction, field emission...GaN nanobelts are synthesized using the chemical vapor deposition method with the catalyst of Ni. The mi- crostrueture, composition and photoluminescence property are characterized by x-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy and photoluminescence spectra. The results demonstrate that the single crystalline GaN nanobelts are grown with a hexagonal wurtzite structure, in width ranging from 500nm to 2μm and length up to 10-20μm. Moreover, a large piezoelectric coefficient d33 of 20pm/V is obtained from GaN nanobelts by an atomic force microscopy and the high piezoelectric property implies that the perfect single crystallinity and the freedom of dislocation for the GaN nanobelt have significant impact on the electromechanical response.展开更多
GaN ultraviolet （UV） photodetectors （PDs） have attracted tremendous attention due to their chemical stability in harsh environments. Although Schottky- contacted GaN-based UV PDs have been implemented with better ...GaN ultraviolet （UV） photodetectors （PDs） have attracted tremendous attention due to their chemical stability in harsh environments. Although Schottky- contacted GaN-based UV PDs have been implemented with better performance than that of ohmic contacts, it remains unknown how the barrier height at local Schottky contacts controls the sensors＇ performance. In this work, the piezotronic effect was employed to tune the Schottky barrier height （SBH） at local contacts and hence enhance the performances of Schottky-contacted metal-semiconductor- metal （MSM） structured GaN nanobelt （NB）-based PDs. In general, the response level of the PDs was obviously enhanced by the piezotronic effect when applying a strain on devices. The responsivity of the PD was increased by 18%, and the sensitivity was enhanced by from 22% to 31%, when illuminated by a 325 nm laser with light intensity ranging from 12 to 2 W/cm2. Carefully studying the mechanism using band structure diagrams reveals that the observed enhancement of the PD performance resulted from the change in SBH caused by external strain as well as light intensity. Using piezotronic effects thus provides a practical way to enhance the performance of PDs made not only of GaN, but also other wurtzite and zinc blende family materials.展开更多
基金Supported by the Program for Changjiang Scholars and Innovative Research Team in University under Grant No IRT-14R48the National Natural Science Foundation of China under Grant No 51272158+2 种基金the Changjiang Scholar Incentive Program of the Education Ministry of China under Grant No[2009]17the China Postdoctoral Science Foundation Funded Project under Grant No 2014M551427the Hujiang Foundation of China under Grant No B14006
文摘GaN nanobelts are synthesized using the chemical vapor deposition method with the catalyst of Ni. The mi- crostrueture, composition and photoluminescence property are characterized by x-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy and photoluminescence spectra. The results demonstrate that the single crystalline GaN nanobelts are grown with a hexagonal wurtzite structure, in width ranging from 500nm to 2μm and length up to 10-20μm. Moreover, a large piezoelectric coefficient d33 of 20pm/V is obtained from GaN nanobelts by an atomic force microscopy and the high piezoelectric property implies that the perfect single crystallinity and the freedom of dislocation for the GaN nanobelt have significant impact on the electromechanical response.
基金Acknowledgements This research was supported by National Science Foundation （NSF）, Multidisciplinary University Research Initiative （MURI） Airforce, Basic Energy Sciences （BES） Department of Energy （DOE） （No. DE- FG02-07ER46394） and the Knowledge Innovation Program of the Chinese Academy of Sciences （Grant No. KJCX2-YW-M13）.
文摘GaN ultraviolet （UV） photodetectors （PDs） have attracted tremendous attention due to their chemical stability in harsh environments. Although Schottky- contacted GaN-based UV PDs have been implemented with better performance than that of ohmic contacts, it remains unknown how the barrier height at local Schottky contacts controls the sensors＇ performance. In this work, the piezotronic effect was employed to tune the Schottky barrier height （SBH） at local contacts and hence enhance the performances of Schottky-contacted metal-semiconductor- metal （MSM） structured GaN nanobelt （NB）-based PDs. In general, the response level of the PDs was obviously enhanced by the piezotronic effect when applying a strain on devices. The responsivity of the PD was increased by 18%, and the sensitivity was enhanced by from 22% to 31%, when illuminated by a 325 nm laser with light intensity ranging from 12 to 2 W/cm2. Carefully studying the mechanism using band structure diagrams reveals that the observed enhancement of the PD performance resulted from the change in SBH caused by external strain as well as light intensity. Using piezotronic effects thus provides a practical way to enhance the performance of PDs made not only of GaN, but also other wurtzite and zinc blende family materials.
