Germanium tin(GeSn)is a group IV semiconductor with a direct band-to-band transition below 0.8 eV.Nonequilibrium GeSn alloys up to 20%Sn content were realized with low temperature(160℃)molecular beam epitaxy.Photodet...Germanium tin(GeSn)is a group IV semiconductor with a direct band-to-band transition below 0.8 eV.Nonequilibrium GeSn alloys up to 20%Sn content were realized with low temperature(160℃)molecular beam epitaxy.Photodetectors and light emitting diodes(LEDs)were realized from in situ doped pin junctions in GeSn on Ge virtual substrates.The detection wavelength for infrared radiation was extended to 2μm with clear potential for further extension into the mid-infrared.GeSn LEDs with Sn content of up to 4%exhibit light emission from the direct band transition,although GeSn with low Sn content is an indirect semiconductor.The photon emission energies span the region between 0.81 and 0.65 eV.Optical characterization techniques such as ellipsometry,in situ reflectometry,and Raman spectroscopy were used to monitor the Sn incorporation in GeSn epitaxy.展开更多
Germanium （Ge） pin photodiodes show clear direct band gap emission at room temperature, as grown on bulk silicon in both photoluminescence （PL） and electro- luminescence （EL）. PL stems from the top contact layer...Germanium （Ge） pin photodiodes show clear direct band gap emission at room temperature, as grown on bulk silicon in both photoluminescence （PL） and electro- luminescence （EL）. PL stems from the top contact layer with highly doped Ge because of strong absorption of visible laser light excitation （532 nm）. EL stems from the recombination of injected carriers in the undoped intrinsic layer. The difference in peak positions for PL （0.73 eV） and EL （0.80 eV） is explained by band gap narrowing from high doping in n＋-top layer. A superlinear increase of EL with current density is explained by a rising ratio of direct/ indirect electron densities when quasi Fermi energy level rises into the conduction band. An analytical model for the direct/indirect electron density ratio is given using simplifying assumptions.展开更多
文摘Germanium tin(GeSn)is a group IV semiconductor with a direct band-to-band transition below 0.8 eV.Nonequilibrium GeSn alloys up to 20%Sn content were realized with low temperature(160℃)molecular beam epitaxy.Photodetectors and light emitting diodes(LEDs)were realized from in situ doped pin junctions in GeSn on Ge virtual substrates.The detection wavelength for infrared radiation was extended to 2μm with clear potential for further extension into the mid-infrared.GeSn LEDs with Sn content of up to 4%exhibit light emission from the direct band transition,although GeSn with low Sn content is an indirect semiconductor.The photon emission energies span the region between 0.81 and 0.65 eV.Optical characterization techniques such as ellipsometry,in situ reflectometry,and Raman spectroscopy were used to monitor the Sn incorporation in GeSn epitaxy.
文摘Germanium （Ge） pin photodiodes show clear direct band gap emission at room temperature, as grown on bulk silicon in both photoluminescence （PL） and electro- luminescence （EL）. PL stems from the top contact layer with highly doped Ge because of strong absorption of visible laser light excitation （532 nm）. EL stems from the recombination of injected carriers in the undoped intrinsic layer. The difference in peak positions for PL （0.73 eV） and EL （0.80 eV） is explained by band gap narrowing from high doping in n＋-top layer. A superlinear increase of EL with current density is explained by a rising ratio of direct/ indirect electron densities when quasi Fermi energy level rises into the conduction band. An analytical model for the direct/indirect electron density ratio is given using simplifying assumptions.
