In GaN quantum dot is a promising optoelectronic material,which combines the advantages of low-dimensional and wide-gap semiconductors.The growth of In GaN quantum dots is still not mature,especially the growth by metal–organic–vapor phase epitaxy(MOVPE),which is challenge due to the lack of 、itin-situ monitoring tool.In this paper,we reviewed the development of In GaN quantum dot growth by MOVPE,including our work on growth of near-UV,green,and red In GaN quantum dots.In addition,we also introduced the applications of In GaN quantum dots on visible light emitting diodes.
A back-illuminated mesa-structure InGaAs/InP charge-compensated uni-traveling-carrier(UTC) photodiode(PD) is fabricated,and its saturation characteristics are investigated.The responsivity of the 40-μmdiameter PD is as high as 0.83 A/W,and the direct current(DC) saturation current is up to 275 mA.The 1-dB compression point at the 3-dB cutoff frequency of 9 GHz is measured to be 100 mA,corresponding to an output radio frequency(RF) power of up to 20.1 dBm.According to the calculated electric field distributions in the depleted region under both DC and alternating current(AC) conditions,the saturation of the UTC-PD is caused by complete field screening at high optical injection levels.
AlGaN photoconductive ultraviolet detectors are fabricated to study their time response characteristics. Persistent photoconductivity,a deterring factor for the detector response time,is found to be strongly related to the grain boundary density in AlGaN epilayers.By improving the crystal-nuclei coalescence process in metal organic vapor phase epitaxy,the grain-boundary density can be reduced,resulting in an-order-of-magnitude decrease in response time.
