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Silicon dioxide(SiO 2 ) thick films have been deposited by plasma enhanced chemical vapor deposition(PECVD) and flame hydrolysis deposition(FHD). PECVD SiO 2 films were obtained at low temperatures(<350°C) by the decomposition of the appropriate mixture of (SiH 4 +N 2 O) gases under suitable rf power and N 2 O/SiH 4 ratio. For low N 2 O/SiH 4 ratio, a refractive index(n) value close to 1.50 is obtained. The deposition rate increased with the increase of rf power. FHD SiO 2 films were produced by the flame hydrolysis reaction of halide materials such as SiCl 4 , POCl 3 and BCl 3 in an oxy-hydrogen torch. The porous SiO 2 layer, under the POCl 3 /BCl 3 ratio deposition condition, has to be consolidated by annealing at around 1300°C.

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In this paper, a 12.5-Gb/s optical transmitter is implemented using 0.13-μm CMOS technology. The optical transmitter that we constructed compensates temperature effects of VCSEL (Vertical cavity surface emitting laser) using auto-power control (APC) and auto-modulation control (AMC). An external monitoring photodiode (MPD) detects optical power and modulation. The proposed APC and AMC demonstrate 5~20-mA of bias-current control and 5~20-mA of modulation-current control, respectively. To enhance the bandwidth of the optical transmitter, an active feedback amplifier with negative capacitance compensation is exploited. The whole chip consumes only 140.4-mW of DC power at a single 1.8-V supply under the maximum modulation and bias currents, and occupies the area of 1280-μm by 330-μm excluding bonding pads.

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