In this paper, a series of boron doped microcrystalline hydrogenated silicon-germanium （p-μc-Si1-xGex：H） was deposited by very high frequency plasma-enhanced chemical vapor deposition （VHF-PECVD） from SiH4 and GeF4 mixtures. The effect of GeF4 concentration on films＇ composition, structure and electrical properties was studied. The results show that with the increase of GeF4 concentration, the Ge fraction x increases. The dark conductivity and crystalline volume fraction increase first, and then decrease. When the GC is 4%, p-μc-Si1-xGex：H material with high conductivity, low activation energy （σ= 1.68 S/cm, E8=0.047 eV）, high crystalline volume fraction （60%） and with an average transmission coefficient over the long wave region reaching 0.9 at the thickness of 72 nm was achieved. The experimental results were discussed in detail.
A new FM transmitter is reported. It adopts a fractional-N PLL synthesizer to realize the FM modulator. An extra offset current has also been applied to eliminate the effects of the mismatch in CP. The chip is fabricated with CSMC 0.5μm DPTM CMOS technology. Experiments show that it achieves THD≤0.08% and SNR≤ 82dB,and the maximum outband emission energy ≤ 90dBc/Hz. Furthermore,it also uses an auto frequency adjusting method to avoid tuning up the external inductances. All these merits are very suitable for FM transmission.
A new system-corrected CMOS audio power AMP is presented. Consisting of four single-end OPAs,this structure is a pseudo-differential system. Compared to conventional CMOS power AMPs, it has the merits of low power consumption, extremely low THD,easy compensation, and good driving capability. With 1st silicon 0.25μm 1P4M CMOS technology and a 3V power supply,the output range can be 4Vpp when driving an 8Ω‖ 300pF load, while its power dissipation is less than 3mW. The THD is better than 0. 003% at 1kHz. A new over-current protection circuit, which can effectively protect the power output circuits on the chip, is also demonstrated.
This letter introduces a 4th order active RC complex filter with 1.SMHz center frequency and 1MHz bandwidth. The total harmonic distortion of the filter is less than -60dB and the image rejection ratio is greater than 60dB. A novel technique is also proposed in this letter to automatically adjust the variation of the time constant. The advantages of the proposed method are its high precision and simplicity. Using 5bits control words, the tuning error is less than ±1.6%.
Chen Dianyu Qi Feitao Sun Weiming Qin Shicai Xiong Shaozhen
A dynamic phosphor-silicate glass （PSG） gettering method is proposed in which the processes of the gettering of Ni by PSC and the crystallizing of α-Si into poly-Si by Ni take place simultaneously. The effects of PSC gettering process on the performances of solution-based metal induced crystallized （S-MIC） poly-Si materials and their thin film transistors （TFTs） are discussed. The crystallization rate is much reduced due to the fact that the Ni as a medium source of crystallization is extracted by the PSC during crystallization at the same time. The boundary between two neighbouring grains in S-MIC poly-Si with PSG looks blurrier than without PSG. Compared with the TFTs made from S-MIC poly-Si without PSC gettering, the TFTs made with PSC gettering has a reduced gate induced leakage current.
An optimized condition for defect passivation by the hot-wire technique was established. Effects of hydrogenation for polycrystalline SiGe （poly-Si1-xGex ） thin films were estimated by investigating the dark conductivity and activation energy that derive from the conductivity as a function of the temperature. The results show that this technique can effectively reduce defects present in poly-Si1-xGex films. By optimizing the substrate and filament temperatures,the treatment can be accomplished in a short time of 20-30min, which is considerably shorter than other hydrogenation techniques.
This paper investigates a simplified metal induced crystallization （MIC） of a-Si, named solution-based MIC （SMIC）. The nickel inducing source was formed on a-Si from salt solution dissolved in de-ionized water or ethanol, a-Si thin film was deposited with low pressure chemical vapour deposition or plasma enhanced chemical vapour deposition as precursor material for MIC. It finds that the content of nickel source formed on a-Si can be controlled by solution concentration and dipping time. The dependence of crystallization rate of a-Si on annealing time illustrated that the linear density of nickel source was another critical factor that affects the crystallization of a-Si, besides the diffusion of nickel disilicide. The highest electron Hall mobility of thus prepared S-MIC poly-Si is 45.6 cm^2/（V· s）. By using this S-MIC poly-Si, thin film transistors and display scan drivers were made, and their characteristics are presented.
