A multi-wafer based semiconductor light absorption structure comprising: a first wafer bonded with a second wafer, wherein the first wafer comprises: a photodiode comprising a light absorption region; a contact region, immediately above the light absorption region and in physical contact with the light absorption region; a first mirror region, wherein the light absorption region is located in between the first mirror region and the contact region, wherein the first mirror region is a metal mirror and is connected to the light absorption region via a first contact metal; and a second mirror region, wherein the contact region is located in between the second mirror region and the light absorption region, wherein the second mirror region is a dielectric mirror; a bonding interface between the first wafer and the second wafer, wherein the bonding interface is located below the light absorption region and is not in physical contact with the light absorption region; wherein a CMOS integrated circuit comprises at least one CMOS transistor and is located in the second wafer, wherein the CMOS integrated circuit is coupled to the contact region via vertical contact vias in the first wafer and the bonding interface; wherein each vertical contact via is provided by a second contact metal in electrical contact with the contact region and a bond pad electrically connected to the CMOS integrated circuit; and wherein the bonding interface uses a metal-plus-dielectric bond to bond the first wafer and the second wafer together and to provide an electrical connection between the bond pad and the CMOS integrated circuit, and between the first mirror region and the CMOS integrated circuit. a first wafer bonded with a second wafer, wherein the first wafer comprises: a photodiode comprising a light absorption region; a contact region, immediately above the light absorption region and in physical contact with the light absorption region; a first mirror region, wherein the light absorption region is located in between the first mirror region and the contact region, wherein the first mirror region is a metal mirror and is connected to the light absorption region via a first contact metal; and a second mirror region, wherein the contact region is located in between the second mirror region and the light absorption region, wherein the second mirror region is a dielectric mirror; a photodiode comprising a light absorption region; a contact region, immediately above the light absorption region and in physical contact with the light absorption region; a first mirror region, wherein the light absorption region is located in between the first mirror region and the contact region, wherein the first mirror region is a metal mirror and is connected to the light absorption region via a first contact metal; and a second mirror region, wherein the contact region is located in between the second mirror region and the light absorption region, wherein the second mirror region is a dielectric mirror; a bonding interface between the first wafer and the second wafer, wherein the bonding interface is located below the light absorption region and is not in physical contact with the light absorption region; wherein a CMOS integrated circuit comprises at least one CMOS transistor and is located in the second wafer, wherein the CMOS integrated circuit is coupled to the contact region via vertical contact vias in the first wafer and the bonding interface; wherein each vertical contact via is provided by a second contact metal in electrical contact with the contact region and a bond pad electrically connected to the CMOS integrated circuit; and wherein the bonding interface uses a metal-plus-dielectric bond to bond the first wafer and the second wafer together and to provide an electrical connection between the bond pad and the CMOS integrated circuit, and between the first mirror region and the CMOS integrated circuit.