Bandwidth and gain enhanced pnp phototransistors for VIS and NIR light IN 180 nm CMOS

Abstract

Two phototransistor concepts with a size of 40×40 μm2 are presented. These devices were implemented in a 180 nm standard CMOS process without process modifications. The use of a special starting material with a low doped p- epitaxial layer on top of the high doped p+ substrate opens the possibility for achieving high bandwidths and responsivities even for deep penetrating light. Optical characterization of the devices was done at 410 nm, 675 nm and 850 nm. Bandwidths up to 67 MHz and responsivities up to 12.35 A/W were achieved. These devices are well suited for integrated optoelectronic circuits (OEICs).