Integration of wavelength signal divider and infrared photodetectors based on the plasma dispersion effect in SiGe/Si

Based on the plasma dispersion effect, a single-mode SiGe wavelength signal divider (WSD) integrated with infrared photodetectors for optical communication at the wavelengths of 1.3 and 1.55 mu m is proposed and fabricated by molecular beam epitaxy. The device performances are measured. The crosstalks of the WSD at a forward modulation bias of 1.2 V are -25 and -18 dB at 1.3 and 1.55 mu m, respectively. The insertion losses are 2.01 and 2.64 dB for 1.3 and 1.55 mu m, respectively. At -5 V reverse bias, the dark currents of the detectors at the 1.3 and 1.55 mu m output branches are 45 and 64 nA, respectively. Photocurrent responsivities of 0.08 and 0.07 A/W for the two detectors at the 1.3 and 1.55 mu m output branches have been achieved. The quantum efficiencies of the whole WSD and detector integration system are estimated to be about 19% and 18.2% for the 1.3 and 1.55 mu m output branches, respectively. (C) 1999 American Institute of Physics. [S0003-6951(99)01412-6].