Solid state radiation transducer (SSRT) assemblies and method for making SSRT assemblies. In one embodiment, a SSRT assembly comprises a first substrate having an epitaxial growth material and a radiation transducer on the first substrate. The radiation transducer can have a first semiconductor material grown on the first substrate, a second semiconductor material, and an active region between the first and second semiconductor materials. The SSRT can also have a first contact electrically coupled to the first semiconductor material and a second contact electrically coupled to the second semiconductor material. The first substrate has an opening through which radiation can pass to and/or from the first semiconductor material.