Search

The P+ a-SiC:H/N+ poly-Si solar cell is simulated by an AMPS-1D device simulator to characterize the new thin film polycrystalline-silicon solar cell. In order to analyze the characteristics of the device, the thickness, working temperature, and impurity concentration for the N+ polysilicon layer are considered. The results show that the performance of the cells shows little change when the thickness of N+ polysilicon varies from 10 to 30 μm. It is concluded that the P+ a-SiC:H/N+ poly-Si solar cell has the highest performance with high open circuit voltages (Voc) of 1.31 V, high conversion efficiency of 17.363% and high fill factor of 0.884. Therefore, the P+ a-SiC:H/N+ poly-Si solar cell has promising future applications [ABSTRACT FROM AUTHOR]

Tunable metamorphic InGaAs partially depleted absorber photodiodes with resonant cavity enhanced structure are fabricated on GaAs substrate. Dark-current densities of 7.2 × 10-7 A/cm2 at 0V and 3.6 × 10-4 A/cm2 at -5 V, a high quantum efficiency of 74.4 % at 1546 nm, and a 3-dB bandwidth up to 12 GHz are achieved. The full width at half maximum of the detector is about 16 nm. Furthermore, through thermal tuning, the peak wavelength red shifts from 1527nm to 1544 nm, and a tuning range of 17nm is realized without fabricating extra tuning electrodes. [ABSTRACT FROM AUTHOR]

The good quality of 200 pairs of highly strained Ino.24GaAs/GaAs multi-quantum-well (MQW) structure is demonstrated by the x-ray diffraction and photoluminescence curves. Large-area modulators based on the pseudomorphic Ino.24GaAs/GaAs MQW are designed and fabricated successfully, where the diameters are not less than 3mm and the working wavelength is extended to 1064nm. The single pass modulation depth is demonstrated to be 0.34 at 1064 nm at a reverse voltage of 80 V . [ABSTRACT FROM AUTHOR]

A separate absorption, grading, charge and multiplication InGaAs/InP avalanche photodiode with ultra low dark current and high responsivity is demonstrated. It has a thin multiplication layer and a planar structure. Through the use of a well and a single floating guard ring to suppress edge breakdown, the device can easily be fabricated by one step epitaxial growth and one step diffusion. The dark current of a 30 μm diameter device is as low as 0.028 nA at punch-through and 0.1 nA at 90% of the breakdown voltage. The responsivity at 1.55 μm is 0.93A/W at unity gain and the multiplication layer is estimated to be less than 300 nm. [ABSTRACT FROM AUTHOR]

We demonstrate a simple scheme of 6.835 GHz microwave source based on the sub-sampling phase lock loop (PLL). A dielectric resonant oscillator of 6.8 GHz is directly phase locked to an ultra-low phase noise 100 MHz oven controlled crystal oscillator (OCXO) utilizing the sub-sampling PLL. Then the 6.8 GHz is mixed with 35 MHz from an direct digital synthesizer (DDS) which is also referenced to the 100 MHZ OCXO to generate the final 6.835 GHz signal. Benefiting from the sub-sampling PLL, the processes of frequency multiplication, which are usually necessary in the development of a microwave source, are greatly simplified. The architecture of the microwave source is pretty simple. Correspondingly, its power consumption and cost are low. The absolute phase noises of the 6.835 GHz output signal are −47 dBc/Hz, −77 dBc/Hz, −104 dBc/Hz and −121 dBc/Hz at 1 Hz, 10 Hz, 100 Hz and 1 kHz offset frequencies, respectively. The frequency stability limited by the phase noise through the Dick effect is theoretically estimated to be better than 5.0 × 10−14τ1/2 when it is used as the local oscillator of the Rb atomic clocks. This low phase noise microwave source can also be used in other experiments of precision measurement physics. [ABSTRACT FROM AUTHOR]