Avalanche gain in GexSi1-x/Si infrared waveguide detectors

Avalanche gain in Ge
x
Si
1-x
/Si heterostructures photodiodes has been measured for the first time. Absorption of infrared radiation occurs in a Ge
x
Si
1-x
/Si strained-layer superlattice (SLS) which serves as a waveguide core, and the avalanche multiplication takes place in one of the Si-cladding layers. Multiplication factors as high as 50 have been obtained for a 1.1-µm wavelength response (x = 0.2). The external absolute sensitivity operating at a multiplication of 10 is 1.1 A/W at 1.3 µm for an uncoated device.