Theoretical study of a group IV p–i–n photodetector with a flat and broad response for visible and infrared detection

We report a theoretical study of a broadband Si/graded-SiGe/Ge/Ge0.9Sn0.1 p–i–n photodetector with a flat response based on modulating thickness of the layers in the active region.The responsivity of the photodetector is about 0.57 A/W in the range of 700 to 1800 nm.This structure is suitable for silicon-based epitaxial growth.Annealing is technically applied to form the graded-SiGe.The photodetector reaches a cut-off wavelength at^2300 nm and a low dark-current density under 3 V reverse bias about 0.17 mA/cm^2 is achieved theoretical at room temperature.This work is of great significance for silicon-based detection and communication,from visible to infrared.

High-performing silicon-based germanium Schottky photodetector with ITO transparent electrode

A near-infrared germanium(Ge)Schottky photodetector(PD)with an ultrathin silicon(Si)barrier enhancement layer between the indium-doped tin oxide(ITO)electrode and Ge epilayer on Si or silicon-on-insulator(SOI)is proposed and fabricated.The well-behaved ITO/Si cap/Ge Schottky junctions without intentional doping process for the Ge epilayer are formed on the Si and SOI substrates.The Si-and SOI-based ITO/Si cap/Ge Schottky PDs exhibit low dark current densities of 33 mA/cm2 and 44 mA/cm2,respectively.Benefited from the high transmissivity of ITO electrode and the reflectivity of SOI substrate,an optical responsivity of 0.19 A/W at 1550 nm wavelength is obtained for the SOI-based ITO/Si cap/Ge Schottky PD.These complementary metal–oxide–semiconductor(CMOS)compatible Si(or SOI)-based ITO/Si cap/Ge Schottky PDs are quite useful for detecting near-infrared wavelengths with high efficiency.

Electrical properties of Si/Si bonded wafers based on an amorphous Ge interlayer

An amorphous Ge（a-Ge） intermediate layer is introduced into the Si bonded interface to lower the annealing temperature and achieve good electrical characteristics. The interface and electrical characteristics of nSi/n-Si and p-Si/n-Si junctions manufactured by low-temperature wafer bonding based on a thin amorphous Ge are investigated. It is found that the bubble density tremendously decreases when the a-Ge film is not immersed in DI water. This is due to the decrease of the –OH groups. In addition, when the samples are annealed at 400 °C for20 h, the bubbles totally disappear. This can be explained by the appearance of the polycrystalline Ge（absorption of H;） at the bonded interface. The junction resistance of the n-Si/n-Si bonded wafers decreases with the increase of the annealing temperature. This is consistent with the recrystallization of the a-Ge when high-temperature annealing is conducted. The carrier transport of the Si-based PN junction annealed at 350 °C is consistent with the trap-assisted tunneling model and that annealed at 400 °C is related to the carrier recombination model.