| dc.description.abstract | In this research, DC pulsed magnetron sputtering method has been applied to grow a single crystal germanium film on the silicon substrate. The energy bandgap of germanium is 0.66eV which is good for absorbing infrared light wavelength and becomes a popular material for photodetectors and solar cells. However, the cost of germanium is higher than silicon. One of the methods to reduce the cost is applied a germanium thin film on the silicon substrate to replace the germanium substrate.
Physical vapor deposition (PVD), the process without toxic and explosive gases, is safer than chemical vapor deposition (CVD). However, the physical lattice mismatch between silicon and germanium makes it difficult to improve the crystal quality and eliminate defects. The defects resulted in the dark current and the carrier recombination, pulsed DC is extended from the DC magnetron sputtering, DCMS, by providing 20V in few microseconds to eliminate the charge accumulation on target. In other word, it can improve the sputtering efficiency during process.
In this research, the high-power impulse magnetron sputtering (HiPIMS) is also applied to a DCMS system. To compare DCMS with HiPIMS, we can find that HiPIMS can ramp up power up to one or two order of magnitudes than DCMS, which can dissociate target material during sputtering. Moreover, a shorter on-time in the impulse means the lower temperature on the target.
In this experiment, the influences on the germanium films by adjusting the sputtering power, hydrogen flow rate, bias voltage, and changing the pulse time (on/off-time) and frequency have been analyzed. As a result, the good quality germanium film has been fabricated with the XRD FWHM 1990 arcsec, and also with only a little tensile stress successfully. | en_US |