OPTICAL AND NOISE CHARACTERISTICS OF AMORPHOUS SI/SIC SUPERLATTICE REACH-THROUGH AVALANCHE PHOTODIODES

In order to improve the performance of the a(amorphous)-Si:H/SiC:H superlattice APD (SAPD), the a-Si:H/SiC:H superlattice reach-through APD’s (SRAPD’s) have been fabricated on ITO(indium tin oxide)/glass substrates by plasma-enhanced chemical vapor deposition (PECVD). For a typical electron-injection SRAPD, the ratio of room-temperature electron and hole impact ionization rates (α/β) is 10.2 at an electric field 3.33 × 106 V/cm as determined by the photocurrent multiplication measurement and checked by the excess noise factor test, the optical gain is 506 at an applied reverse-bias VR = 18 V and an incident power Pin = 5 µW emitted from a He-Ne laser, the rise time is 1 us at a load resistance Rl = 1 kΩ, and the excess noise factor is 6.53 at a multiplication M = 48. These results are better than those of the other amorphous photodetectors ever reported. Some performances of homojunction a-Si : H reach-through APD’s (RAPD’s) is also described for the purpose of comparison. © 1990 IEEE