We investigated growth of GaN pn-junction layers grown on silicon（111） by plasma-assisted molecular beam epitaxy system and its application for photo-devices. Si and Mg were used as n- and p-dopants, respectively. T...We investigated growth of GaN pn-junction layers grown on silicon（111） by plasma-assisted molecular beam epitaxy system and its application for photo-devices. Si and Mg were used as n- and p-dopants, respectively. The reflection high energy electron diffraction images indicated a good surface morphology of GaN pn-junction layer. The thickness of GaN pn- junctions layers was about 0.705 nm. The absence of cubic phase GaN showed that thiS layer possessed hexagonal structure. According to XRD symmetric rocking curve ω/2θ scans of （0002） plane at room temperature, the full width at half-maximun of GaN pn-junction sample was calculated as 0.34°, indicating a high quality layer of GaN pn-junction. Surprisingly, there was no quenching of the A1 （LO） peak, with the presence of Si- and Mg-dopants in sample. The pn-junctions sample has a good optical quality which was measured by the photoluminescence system. For photo-devices applications, Ni and A1 were used as front and back contacts, respectively. The current-voltage characteristics of the devices showed the typical rectifying behavior of heterojunction. The photo-current measurement was performed using a visible-lamp under forward and reverse biases. From the temperature-dependent measurements, the current at low bias exhibited much stronger temperature dependence and weaker field dependence. The effect of thermal annealing on front contact Ni was also carried out. The front contact Ni was annealed at 400 and 600 ℃ for 10 min in the nitrogen ambient. The results showed that 600 ℃ treated sample had a higher gain at 1.00 V/e than 400 ℃ treated and untreated samples.展开更多
The group Ⅲ nitrides are an important class of materials with aplications in UV and visible optoelectronics,high temperature electronics,cold cathodes and solar blind detectors.In recent years,with the realisation of...The group Ⅲ nitrides are an important class of materials with aplications in UV and visible optoelectronics,high temperature electronics,cold cathodes and solar blind detectors.In recent years,with the realisation of nitride based LEDs,the use of GaN IED has the potential to compete with 1raditional filament and discharge lamps,for the provision of white lighting,and there has been an explosion of interest in the MOCVD growth of GaN based materials with an increasing focus on large area multiwafer reactors and wafer uniforrmity.This paper will review the design philosophy and characteristics of close-coupled showerhead reactors,relating these to the requirements of group Ⅲ-nitride growth,and will present a selection of data resulting from the operation of such equipment.These results suggest that the close coupled showerhead style of reactor is very suitable for the growth of GaN based structures in both research and production environments.展开更多
文摘We investigated growth of GaN pn-junction layers grown on silicon（111） by plasma-assisted molecular beam epitaxy system and its application for photo-devices. Si and Mg were used as n- and p-dopants, respectively. The reflection high energy electron diffraction images indicated a good surface morphology of GaN pn-junction layer. The thickness of GaN pn- junctions layers was about 0.705 nm. The absence of cubic phase GaN showed that thiS layer possessed hexagonal structure. According to XRD symmetric rocking curve ω/2θ scans of （0002） plane at room temperature, the full width at half-maximun of GaN pn-junction sample was calculated as 0.34°, indicating a high quality layer of GaN pn-junction. Surprisingly, there was no quenching of the A1 （LO） peak, with the presence of Si- and Mg-dopants in sample. The pn-junctions sample has a good optical quality which was measured by the photoluminescence system. For photo-devices applications, Ni and A1 were used as front and back contacts, respectively. The current-voltage characteristics of the devices showed the typical rectifying behavior of heterojunction. The photo-current measurement was performed using a visible-lamp under forward and reverse biases. From the temperature-dependent measurements, the current at low bias exhibited much stronger temperature dependence and weaker field dependence. The effect of thermal annealing on front contact Ni was also carried out. The front contact Ni was annealed at 400 and 600 ℃ for 10 min in the nitrogen ambient. The results showed that 600 ℃ treated sample had a higher gain at 1.00 V/e than 400 ℃ treated and untreated samples.
文摘The group Ⅲ nitrides are an important class of materials with aplications in UV and visible optoelectronics,high temperature electronics,cold cathodes and solar blind detectors.In recent years,with the realisation of nitride based LEDs,the use of GaN IED has the potential to compete with 1raditional filament and discharge lamps,for the provision of white lighting,and there has been an explosion of interest in the MOCVD growth of GaN based materials with an increasing focus on large area multiwafer reactors and wafer uniforrmity.This paper will review the design philosophy and characteristics of close-coupled showerhead reactors,relating these to the requirements of group Ⅲ-nitride growth,and will present a selection of data resulting from the operation of such equipment.These results suggest that the close coupled showerhead style of reactor is very suitable for the growth of GaN based structures in both research and production environments.
