Study Of Ohmic Contact Al Electrodes And Trial Research Of Photodetector

Ge/Si quantum dots material with three dimensional quantum confinement effect have shown a great application prospect in photoelectric device. In this thesis, some basic researches on Ge/Si photoelectric detect device and the preparation of ohmic contact Al electrode by magnetron sputtering were conducted. The evolution of morphologies and photoelectric performance of Al film grown at different sputtering power, deposition thickness, annealing temperature were studied. In addition, the trial-manufacture of optical detector was developed.Firstly, The Ge/Si quantum dots were prepared by using the magnetron sputtering equipment, and then the dots’density and size were regulated by annealing. By using atomic force microscopy (AFM) and Raman spectroscopy, the formation mechanism and evolution rule of Ge islands were analyzed when annealing temperature increase from550℃to650℃. The AFM images revealed that the volume and density of the quantum dots were increased when the annealing temperature increased. The quantum dots’density reached about3.5×1010cm-2when the sample was annealed at650℃for10min. By analyzing the Raman spectrum, it was found that Ge-Ge peak blue shifted when annealing temperature increased. Various factors that could cause a blue shift were analyzed, mainly due to the dislocation which declined along with annealing temperature increasing.The evolution of morphologies and photoelectric performance of Al film grown at different sputtering power, deposition thickness, annealing temperature were studied. The surface morphologies and element contents were analyzed by detection equipment such as SEM and EDS. The experimental results indicated that the optimum parameters for Al film forming was as following settings:the sputtering power was100W, deposition thickness was600nm and the annealing temperature was550℃. The effect of Al-Si ohmic contact with different annealing time was studied and the I-V characteristic curve was tested. The result showed that there was no ohmic contact in the prototype without annealing and annealing5minutes. Al film could form good ohmic contact when the annealing temperature was550℃and the annealing time were10minutes and30minutes respectively. The contact resistance with annealing30minutes was lower than others.Based on our recent work, PIN structure Ge/Si quantum dots based photo detector research had been carried out. Three prototype devices have been made and. the I-V characteristic curve was tested. By adjusting Al electrode, P-type layer, quantum dot layers and some other parameters, the final device (#003) exhibits a good I-V characteristic.