Optical study of Ge quantum dots and infrared photodetectors

Stacked Ge quantum dots were grown on Si(100) by ultra-high vacuum chemical vapor deposition (UHV/CVD). Obvious blueshift (87 meV) observed from PL spectrum under 10 K demonstrates strong quantum confinement in Ge dots. Based on the material, PIiN structure quantum dot infrared photodetectors (QDIPs) were fabricated. At room temperature, I-V measurement showed a low dark current density of 1.7 × 10^-6 A/cm² at -3 V. The maximum photocurrent responsivity of 0.52 A/W at 774 nm was achieved, and 0.043 mA/W at 1.31 μm was found. The dots layers were considered to trap the light in the intrinsic region, and thus increase the absorption. Finally, samples of structural optimization were proposed.