本論文的主要目的是探討具非晶接面及溝渠式電極之矽質金屬-半導體-金屬光偵測器的暗電流基本機制，並且藉以降低元件之暗電流而提升其訊雜比。利用梯度高能隙非晶合成物結構及附加不鏽鋼濾網的電漿助長化學氣相沈積系統沈積非晶薄膜等技巧可降低元件的暗電流，且效果良好。非晶位障層對金屬-半導體-金屬光偵測器而言，不僅可以降低暗電流，更可提升暗電流對溫度的穩定性。 In this thesis, dark-current characteristics of the Si-based MSM-PD with amorphous-crystalline heterojunction and trench electrodes were studied. The current transport mechanisms across the amorphous-crystalline heterojunction and the metal-semiconductor Schottky barrier had been discussed, and the obtained concepts, e.g. using materials having a higher activation energy and a higher Schottky barrier, could be helpful to suppress the device dark current. Although using trench electrodes might result in a little higher device dark current, but the benefits were the improvements of the device knee voltage, responsivity, and response speed. However, the photo-to-dark current ratio is an important issue for a MSM-PD. So the device responsivity should be considered when its dark-current was suppressed, and accordingly, a graded high bandgap amorphous alloy could be employed for the amorphous-crystalline heterojunction to enhance device photo-to-dark current ratio. Plasma damages on the crystalline silicon (c-Si) substrate, caused by ion bombardments during deposition of amorphous layer, could increase the dark-current magnitude of an a-Si:H/c-Si MSM-PD, because the induced defect states on c-Si substrate served as generation centers in the reverse-biased junction. The plasma damages could be reduced significantly by using a deposition technique i.e. attaching a s.s. reticulate mesh to the upper (cathode) electrode of the PECVD (plasma-enhanced chemical vapor deposition) system during deposition of the i-a-Si:H layer.