We discuss the PL spectra of the InN band gap. The InN thin film epitaxy grows on both Si (111) and sapphire (0001) by the PA-MBE (molecular beam epi). We change different grown conditions to improve the sample quality. In experiment part, the first step is to make sure the sample is really InN, using X-ray diffraction. And then we compare the quality of all sample, by the FWHM of X-ray diffraction rocking curve and the SEM pictures.

The experiment divided into two parts. One is silicon solar cell process. The other is InGaN solar cell process. Borosilicafilm solution spin onto the n-type silicon (111) substrate and spread through the high-temperature furnace tube to form a p-n junction silicon solar cell. Then, evaporate top and rear contact by electron beam evaporation system. InGaN p-i-n structure solar cell grows on sapphire substrate by plasma-assisted molecular beam epitaxy system (PA-MBE) and its process is by repeated photolithography, inductive coupled plasma etching and wet etching. In the device fabrication process, the first is defining the sample size(mesa). Second, etched to the n-type GaN layer, and then coated metal as electrode. Finally, we get the device. In the measurement, the measurement of I-V curve of samples in the light by solar simulator of AM1.5 G light source observe open circuit voltage, short circuit current, fill factor, and efficiency. In addition, we measure the external quantum efficiency of the samples by IPCE and observe the photoelectric conversion efficiency of samples at different wavelength. Observed the sample quality and the indium composition of InGaN layer by XRD. We observe the InGaN band gap shift by variable-temperature photoluminescence spectra.

In order to develop high speed photo-electronic device, first, we grew one layer of GaN by MOPVE to decline lattice mismatch. Then we used PA-MBE to grow AlxGa1-xN/GaN heterostructure III-V semiconductor. Via changing the content of aluminum, we can confer the characteristic of these samples. In these samples, we controlled the content of aluminum by changing the vapor of aluminum. And then we used X-ray diffraction, SEM, AFM, low temperature Hall measurement and SdH to study the characteristic of these samples. Throughout X-ray diffraction, the aluminum content x are 1.76%, 2.3%, 14.33%, 22.03% and 37.26%. Due to (004) AlGaN Rocking Curve F.W.H.M. are only 300 arcsec, the quality of the five samples are extraordinary. In addition, SEM and AFM measurement indicate that this series samples¡¦ interface are very smooth, and the roughest sample is only 2nm. It can make sure that samples were grown in mode of two-dimensional (2D). With low temperature Hall measurement, we can find out the Coulomb scattering which is from the defect are very small in the sample A, B, C, D. And the mobility of this series samples are very high, the highest mobility is sample A at 8K which is 19593 cm2/Vs. We can observe the oscillation of the sample C, D obviously in SdH measurement indicate that the 2DEG is confined in the potential well.