Systems and methods for forming thin bulk junction thermoelectric devices in package

This disclosure relates to an integrated thermoelectric cooler and methods for forming thereof. The integrated thermoelectric cooler can include a plurality of thermoelectric rods located between the detector substrate and a system interposer. The detector substrate and the system interposer can directly contact ends of the thermoelectric rods. The integrated thermoelectric cooler can be formed by forming the plurality of thermoelectric rods on reels, for example, and the plurality of thermoelectric rods can be thinned down to a certain height. The thermoelectric rods can be transferred and bonded to the system substrate. An overmold can be formed around the plurality of thermoelectric rods. The height of the overmold and thermoelectric rods can be thinned down to another height. The thermoelectric rods can be bonded to the detector substrate. In some examples, the overmold can be removed.