In order to take advantage of silicon nitride films as an ILD layer on GaAs devices, the ICP CVD silicon nitride films were investigated by parametric study of effects of deposition parameters on the physical properties of silicon nitride film deposited in the range of 50 ~ 200oC temperature. Good quality of films could be achieved, including low moisture absorption, low H content (<15 at.%), good resistance to BOE etching (<50 Aå/min), smooth film surface (2.0 nm roughness), and reasonable film stress, as compared to the conventional PECVD nitride film, while the process temperature is much lower than the conventional PECVD process. This silicon nitride film was applied to the GaAs HBT device structure and showed very promising results of the gap-filling capability and planarization for next level of metallization. These results indicate the possibility of using the ICP CVD silicon nitride films as an ILD layer in the GaAs devices instead of polymer type dielectrics, which typically require a long cure time at high temperature of 300oC or higher.
In this paper, a novel low-damage silicon nitride passivation for 100 nm In 0.45 AlAs/In 0.4 GaAs MHEMTs has been developed using remote ICPCVD. The silicon nitride deposited by ICPCVD showed higher quality, higher density, and lower hydrogen concentration than those of silicon nitride deposited by PECVD. In particular, we successfully minimized the plasma damage by separating the silicon nitride deposition region remotely from ICP generation region, typically with distance of 34 cm. The silicon nitride passivation with remote ICPCVD has been successfully demonstrated on GaAs MHEMTs with minimized damage. The passivated devices showed considerable improvement in DC characteristics and also exhibited excellent RF characteristics (f T of 200 GHz).The devices with remote ICPCVD passivation of 50 nm silicon nitride exhibited 22 % improvement (535 mS/mm to 654 mS/mm) of a maximum extrinsic transconductance and 20 % improvement (551 mA/mm to 662 mA/mm) of a maximum saturation drain current compared to those of unpassivated ones, respectively. The results achieved in this work demonstrate that remote ICPCVD is a suitable candidate for the next-generation MHEMT passivation technique.
We report advancement in C-band DWDM lasers with ultra-high coupled optical power (>100mW) operated at 500mA. The laser also showed excellent RIN (≥-168dB) and narrow linewidth (<25kHz) suitable for +100km transmission. Life test (>3000hr) performance was robust.
IntroductionHigh power diode lasers are the building blocks for dense wavelength division multiplexing (DWDM) long-haul optical link. The increased power enables the +100km long-haul transmission and compensates the insertion loss. Using DWDM technology, several wavelengths, typically in 1550nm C-band, can simultaneously multiplex signals to expand bandwidth over a strand of fiber [1].Recently, we have made further technological advancement in high power distributed feedback (DFB) lasers that show excellent power, narrow spectral linewidth and low relative intensity noise (RIN) required for C-band, +100km long-haul transmission. We als demonstrate good manufacturability and excellent reliability performance.
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