The thermal impedance of p-i-n diodes integrated on semiconductor-on-insulator substrates can be reduced with thermally conducting vias that shunt heat across thermal barriers such as, e.g., the thick top oxide cladding often encapsulating the p-i-n diode. In various embodiments, one or more thermally conducting vias extend from a top surface of the intrinsic diode layer to a metal structure connected to the doped top layer of the diode, and/or from that metal structure down to at least the semiconductor device layer of the substrate.