Herstellung und Charakterisierung von ultraschnellen Photodetektoren

This work reports on the fabrication and characterization of ultrafast vertical metal-silicon-metal (MSM) Schottky-barrier-photodiodes for the detection of visible and infrared light. The devices are manufactured on an epitaxial buried CoSi_2 ground plate on silicon consisting of a high quality single crystalline silicon layer sandwiched between the buried CoSi_2 layer and a top semitransparent metal layer. For wavelengths shorter than 1.1 #mu#m, electron-hole pairs are generated in the Si. They are separated by an internal electrical field and accelerated towards the metal electrodes. For shorter wavelengths, Si becomes transparent and carriers are emitted from the internal semiconductor-metal interface. A photocurrent is produced. This so-called internal photoeffect is governed by different carrier dynamics: hot electrons or holes are injected from the metal layers into the silicon. Their large excess energy leads to extremely fast electrical pulses. A new theoretical model for the hot carrier dynamics inside the detector is proposed and examined by detailed simulations. The resulting temporal response of the detectors was measured with a new setup, using a modelocked Ti:sapphire laser and an optical parametric oscillator, which generates ultrafast optical pulses (170 fs) at IR wavelengths. At 820 nm the MSM photodiodes show an impulse response as short as 3.5 ps FWHM for Si(100) and 6.7 ps FWHM for Si(111). For the first time, the temporal response of MSM photodiodes was investigated at 1250 and 1560 nm wavelengths with femtosecond resolution. MSM photodiodes with different top metallization (Cr,Ti and Pt) were analyzed. (orig.)71 refs.Available from TIB Hannover: RA 831(3687) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman