Hydrogenated amorphous silicon (a-Si:H) thin films have been prepared by DC magnetron sputtering, and the effect of
sputtering power, the hydrogen flow rate on deposition rate and the optical properties of a-Si:H thin films have been
investigated. The hydrogen content (CH) of the films was calculated by Fourier transform infrared (FTIR) spectroscopy
method, the maximum CH was obtained at 11at. %,and a bandgap of a-Si:H thin films was changed from 1.43 to 2.25 eV
with different CH. It was found that the refractive index (n) and extinction coefficient (k) of the prepared films decreased
with the increase of CH. The results provided experimental basis for preparing a-Si:H thin films with special performance and structure .
KEYWORDS: Semiconductor lasers, Ions, Reflectivity, Antireflective coatings, Optical coatings, Ion beams, High power lasers, Numerical simulations, Thin film coatings, Aluminum
The characteristics of GaAs-based semiconductor Laser with antireflective and high reflective coatings are studied. The film designs are optimized with programmed software using the film design program for a double-layer scheme. According to the numerical simulations, the different double-layer with proper parameters is coated onto GaAs-based semiconductor Laser. The thickness of double layers is also calculated using the software taking account of antireflective and high reflective coating in the design of double layer film. With the optimized design of double-layer film, the power properties of GaAs-based semiconductor Laser are improved, and the experimental results satisfy the application requirements as semiconductor Laser.
In this paper, we have designed a laser structure with separate confinement single quantum well (SCH-SQW )and have grown the laser structure by MOCVD .Moreover we have also fabricated broad area structure .The lasers are cleaved into bars and coated with high and low reflectivity films (approximate 95% and 5%).The measured results of the device show that its threshold current is 1.95A ,The CW output power is 2W ,and the peak wavelength of the device is 910nm±2nm .
KEYWORDS: Video, Image sensors, CMOS sensors, Very large scale integration, Microcontrollers, Digital image processing, Data integration, Clocks, Digital signal processing, Digital imaging
CMOS process is mainstream technique in VLSI, possesses high integration. SE402 is multifunction microcontroller, which integrates image data I/O ports, clock control, exposure control and digital signal processing into one chip. SE402 reduces the number of chips and PCB's room. The paper studies emphatically on USB video image controller used in CMOS image sensor and give the application on digital still camera.
In this paper ,high quality AlGaAs/GaAs single quantum well(SQM) structure is grown on (100) GaAs substrate by molecular beam epitaxy (MBE) system. Optical and structural characteristic of the film was studied by low temperature (10K) photoluminescence (PL) and X-ray double crystal diffraction method. Using X-ray kinematical theory, we calculated the structure parameters of each samples, the reason for the appearance of the interfering fringes and splitting peaks in double crystal rocking curve were analyse theoretically. The deep levels which affect character of the material and laser are also discussed. The experimental results show that measuring methods of the photoluminescence and X-ray double crystal diffraction are very important for testing the quality of quantum wells and improving the MBE technology.
In order to enhance the conversion efficiency and output power of semiconductor lasers, extend its lifetime, the contact resistance has to be reduced. This paper introduces the recent results obtained about the semiconductor laser Ohmic contact experimental study. In our work, AuZn film was evaporated on to the P side of the laser epitaxial wafer, and AuGeNi on to N side. By choosing the optimum alloying temperature of 400 degree(s)C, we obtained the lowest contact resistance. After this process, AR and HR films were sputtered on to the two facets of the laser cavity. Finally, the following results were obtained for the laser performance: central wavelength (lambda) 0 equals 808 nm, threshold current density Jth equals 300 - 470 A/cm2, CW output power P equals 3W, resistance R equals 0.06 (Omega) (for a laser stripe of 150 micrometers , cavity length of 1 mm).
By using a recently modified LPE technique, extremely uniform InGaAsP/GaAs SCH SQW structure materials could be grown reproducibly. Single stripe lasers with 150 um emitting aperture generate 4.0 W in CW by improvement of waveguiding parameters and ohmic contact process.
In this work, we report Al-free InGaAsP/GaAs separate confinement heterostructure single quantum well structures for lasers emitting at 808 nm are grown by enhanced liquid phase epitaxy. The highest continuous wave output power is 4 W for lasers with coated facts. The differential efficiency is 1.32 W/A. The record characteristic T0 of the laser is estimated to be about 218 K between 10 degree(s)C and 40 degree(s)C from the temperature dependence of the threshold current density Jth.
KEYWORDS: Semiconductor lasers, Liquid phase epitaxy, Quantum efficiency, High power lasers, Waveguides, Heterojunctions, Temperature metrology, Quantum wells, Diodes, Chemical species
A detailed operating characteristics of InGaAsP/GaAs separate confinement heterostructure single-quantum-well wide-stripe lasers emitting at 808 nm grown by liquid phase epitaxy is reported. The temperature dependences of the lasing wavelength (lambda) , the threshold current density Jth and differential quantum efficiency (eta) d are studied. The effects of the cavity length L on the threshold current density Jth and the differential quantum efficiency (eta) d are studied. The threshold current density Jth increases with increasing temperature T. But the increase of Jth with temperature T is slightly deviated from the exponential dependence. The data fitting of Jth with between 10 degree(s)C and 40 degree(s)C demonstrates a record characteristic temperature T0 of 218 K, indicating a minor influence of temperature on Jth.
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