Analysis of Capacitance-Voltage-Temperature Characteristics of GaN High-Electron-Mobility Transistors

The capacitance-voltage characteristics of AIGaN/GaN high-electron-mobility transistors （HEMTS） are measured in the temperature range of 223-398K. The dependence of capacitance on frequency at various temperatures is analyzed. At lower temperatures, the capacitance decreases only very slightly with frequency. At higher frequencies the curves for all temperatures tend to one capacitance value. Such behavior can be attributed to the interface states or the dislocations.

Antireflection properties and solar cell application of silicon nanoscructures

Silicon nanowire arrays（SiNWAs） are fabricated on polished pyramids of textured Si using an aqueous chemical etching method.The silicon nanowires themselves or hybrid structures of nanowires and pyramids both show strong anti-reflectance abilities in the wavelength region of 300-1000 nm,and reflectances of 2.52%and less than 8%are achieved,respectively.A 12.45%SiNWAs-textured solar cell（SC） with a short circuit current of 34.82 mA/cm^2 and open circuit voltage（K_（oc）） of 594 mV was fabricated on 125×125 mm^2 Si using a conventional process including metal grid printing.It is revealed that passivation is essential for hybrid structure textured SCs,and K_（oc） can be enlarged by 28.6%from 420 V to 560 mV after the passivation layer is deposited.The loss mechanism of SiNWA SC was investigated in detail by systematic comparison of the basic parameters and external quantum efficiency（EQE） of samples with different fabrication processes.It is proved that surface passivation and fabrication of a metal grid are critical for high efficiency SiNWA SC,and the performance of SiNWA SC could be improved when fabricated on a substrate with an initial PN junction.

Progress in Group Ⅲ nitride semiconductor electronic devices

Recently there has been a rapid domestic development in group iII nitride semiconductor electronic materials and devices. This paper reviews the important progress in GaN-based wide bandgap microelectronic materials and devices in the Key Program of the National Natural Science Foundation of China, which focuses on the research of the fundamental physical mechanisms of group III nitride semiconductor electronic materials and devices with the aim to enhance the crystal quality and electric performance of GaN-based electronic materials, develop new GaN heterostructures, and eventually achieve high performance GaN microwave power devices. Some remarkable progresses achieved in the program will be introduced, including those in GaN high electron mobility transistors （HEMTs） and metal-oxide-semiconductor high electron mobility transistors （MOSHEMTs） with novel high-k gate insulators, and material growth, defect analysis and material properties of InAlN/GaN heterostructures and HEMT fabrication, and quantum transport and spintronic properties of GaN-based heterostructures, and high- electric-field electron transport properties of GaN material and GaN Gunn devices used in terahertz sources.