engleski

Physical characteristics and applications of nanometer thin boron-on-silicon layers in silicon detector devices

Deposition of ultra-thin pure amorphous boron (PureB) layers directly on silicon have in recent years been used to fabricate various types of silicon detector devices that have I-V characteristics with ideality factor equal to 1 and low dark currents together with excellent responsivity, stability and robustness. In this thesis, PureB layers were examined with material characterization techniques such as X-ray photoemission spectroscopy and spectroscopic ellipsometry. An extensive electrical characterization is performed on devices with PureB layers at temperatures from room temperature down to 77 K in a cryogenic liquid nitrogen system, which provided an understanding of the carrier transport across the PureB-silicon interface and conduction through the PureB layers. The main mechanism for carrier conduction through the PureB layer was identified as variable range hopping conduction. For ultra-thin PureB layers with thickness lower than 2 nm, the holes can tunnel to an aluminum contact ordinarily used on PureB layers. An interfacial hole layer at the PureB/Si interface was found to be able to account for the effective blocking of electron injection from the bulk. The information gathered on the physical and electrical characteristics of the PureB-on-silicon layers was used to develop an electrical model of the PureB layer and its interface with silicon. Incorporation of the thus defined model in technology computer aided design (TCAD) software provided an efficient tool for proposing and simulating novel photodiode structures integrating PureB layers to exploit the attractive electrical and optical characteristics. A detailed TCAD analysis was performed on guard ring optimization of PureB devices, optimization of PureB single photon avalanche diode (SPAD) geometry, reduction of indirect optical crosstalk in a SPAD array, and novel silicon drift detectors with the drift field induced by PureB-coated trenches.

PureB, material characterization, X-ray photoemission spectroscopy, XPS, spectroscopic ellipsometry, electrical characterization, low-temperature measurements, PureB model, variable range hopping conduction, tunneling, guard ring optimization, perimeter effects, single photon avalanche diodes, SPAD, SPAD array, dark count rate modeling, 2D DCR modeling, indirect optical crosstalk reduction, drift detectors

nije evidentirano