Monolithic focal plane array circuit and method thereof

A method of fabricating a monolithic sensor device, the method comprising:

• providing a partially completed semiconductor read-out integrated circuit (ROIC) substrate comprising a silicon substrate, an ROIC device formed overlying the silicon substrate, and a first dielectric layer formed overlying the ROIC device and the silicon substrate;
• forming a first cavity region within a portion of the first dielectric layer exposing a first portion of the ROIC device;
• forming an elemental semiconductor sensor device overlying the ROIC device within the first cavity region;
• forming a first dielectric material overlying the elemental semiconductor sensor device within the first cavity region;
• forming a second cavity region within a portion of the first dielectric layer exposing the elemental semiconductor sensor device and the ROIC device;
• subjecting the elemental semiconductor sensor device and the ROIC device to one or more IC processing steps;
• forming a second dielectric material overlying the elemental semiconductor sensor device and the ROIC device within the second cavity region;
• forming a third cavity region within the second dielectric material overlying at least a portion of the elemental semiconductor sensor device;
• forming a buffer material overlying the elemental semiconductor sensor device within the third cavity region, wherein forming the buffer material comprises a selective area heteroepitaxy process;
• forming a plurality of compound semiconductor (CS) photodetector device materials overlying the buffer material within the third cavity region to form a CS photodetector device overlying the elemental semiconductor sensor device, wherein forming the CS photodetector device comprises a selective area heteroepitaxy process;
• and
• forming a second dielectric layer overlying the CS photodetector device, the second dielectric material, and the first dielectric layer.