A method for fabricating a thermal management substrate comprises acts of ion-implanting a substrate material to form a substrate layer, a ion-implanted layer, and an overlay layer; bonding a handle wafer to the overlay layer with a SiO.sub.2 bonding layer; splitting the ion-implanted wafer at the ion-implanted layer, resulting in a handle wafer SiO.sub.2 bonded with the overlay layer; depositing an insulating layer onto the overlay layer; and removing the handle wafer, whereby the resulting thermal management substrate comprises an overlay layer epitaxially fused with the insulating layer.