Study And Improvement Of Silicon Based Germanium Quantum-dot Near Infrared Photodetecter

The increase of speed and packing density is leading to the continuousminiaturization of electronic devices. Conventional microelectronic devicesare reaching the minimum size limit. Nanoelectronic devices, which areworking based on quantum mechanics, have drawn more and more attentions.Silicon based germanium quantum-dot (QD) devices are highly focused for itscompatibility with mature VLSI processing technology. An additionalrestriction of the carrier motion and discrete energy spectrum offer significantadvantages of QD devices over quantum-well structures and bulk layer inoptical properties, which make them the competitive candidates of infraredphoto-detectors. Si-based Ge quantum-dot infrared photo-detector (QDIP),working in the near-IR spectral range, was investigated in this thesis.To improve the absorptivity in p-i-n vertical QDIP at given wavelength,then quantum efficiency, absorptivities of devices with different spacerthickness, number of periods and with Silicon-on-insulator substrate andanti-reflecting film were calculated by a matlab program and compared witheach other. Optimized device structure is proposed based on the simulation.Materials were analyzed by XRD, Raman, AFM and Photo-luminescence.Samples with optimized structure but different substrates and differentanti-reflecting films were successfully fabricated.Measurements of I-V characteristic, dark current and responsivity hadbeen carried out. Comparisons between different devices and to un-optimizeddevices show that optimized structure improves the responsivity at 1.31umremarkably, and Si3N4 anti-reflecting film with appropriate thicknessimproves this responsivity highly, which also have been shown in simulation.