CARRIER TRAPPING IN ULTRAFAST METAL-SEMICONDUCTOR-METAL PHOTODETECTORS ON INGAAS/GAAS-ON-GAAS SUPERLATTICES

High-resolution time-resolved measurements and deep level transient spectroscopy (DLTS) measurements on InxGa1-xAs/GaAs-on- GaAs superlattices grown by molecular-beam epitaxy with InAs content x from 0% to 63% are presented. The pulse response of metal-semiconductor-metal photodetectors (MSMPDs) on these layers varies from transit-time-limited responses to ultrafast lifetime-limited responses with electron and hole lifetimes of 3 and 15 ps. DLTS measurements on the superlattices and a two-dimensional self-consistent numerical simulation of the MSMPDs pulse response indicate a strong influence of the oxygen related electron trap EL3 on the electron lifetimes. The dark currents range between 500 pA and 700 nA at 5 V for 20×20 μm2 devices and the spectral response shows cutoff wavelengths up to 1550 nm. © 1995 American Institute of Physics.