The Extraction of Minority Carrier Lifetime from the Current-Voltage Characteristics of Si/Si1−xGex Devices

ABSTRACTThe extraction of recombination lifetime from the current-vol tage characteristics of diode structures containing Si1−xGex strained layers is discussed. Electrical measurements are used in conjunction with computer simulations to extract minority carrier lifetime in Si1−xGex layers with various oxygen concentrations. The minority carrier lifetime in Si1−xGex increases from several psec at an oxygen concentration of 2×1020 cm−3, to greater than 0.5 μs at concentrations below 3×1017 cm−3. The structures are analyzed for sensitivity of the current characteristics to Si1−xGex minority carrier lifetime. Calculations predict that the maximum lifetime which can be extracted from such structures is greater than 100 μsec. However, due to limitations imposed by perimeter currents, the maximum lifetime which can be extracted from our diode structures is on the order of 3 μsec. Maximizing area to perimeter ratio of the diode structures and moving the Si1−xGex-SiO2 interface away from the active device region is required in order to increase the maximum extracted lifetime from such structures.