Interfacial composition and electrical properties of PtSi/Si1−xGex/Si diodes by molecular beam epitaxy (MBE) and pulsed laser deposition (PLD)

By combining pulsed laser deposition (PLD) and molecular beam epitaxy (MBE), it has been demonstrated that PtSi/strained Si1−xGex (x=0,0.2 and 0.25) Schottky barrier detector (SBD) with extended cutoff wavelengths. Pt was deposited by PLD on the Si1−xGex alloys with a thin Si sacrificial cap layer grown by MBE. By the reaction of deposited Pt film on Si sacrificial cap layer silicide SBDs have been fabricated. Auger electron depth profiling was performed on the films before and after in vacuo annealing to study the redistribution of composition in the reactions. The variation of the barrier height of the junctions with the Ge fraction x was studied, it was found to follow the same change as the bandgap of strained Si1−xGex, and the cutoff wavelength has been extended beyond 10 μm in PtSi/strained Si1−xGex SBDs. In addition, the Schottky barrier height (SBH) of PtSi/Si1−xGex/Si has been found to vary between 0.12 and 0.58 eV in the temperature range 77–293 K. At 293 K, the ideality factor has been found to be 2.00 and 1.32 for PtSi/Si0.80Ge0.20 and PtSi/Si0.75Ge0.25 diodes, respectively.