Heterostructure with sacrificial layer

A heterostructure comprising:

• a substrate structure having a patterned surface, the substrate structure including:
• a sapphire substrate;
• and
• a set of group III nitride buffer layers directly adjacent to the substrate;
• a set of group III nitride device layers located adjacent to the substrate structure;
• and
• a sacrificial layer located between the substrate structure and the set of group III nitride device layers, wherein the sacrificial layer includes at least one sub-layer including a first set of regions formed of a first material and a second set of regions located laterally adjacent to the first set of regions and having a composition different from the first material, wherein the first material has bandgap smaller than a bandgap of each of the set of group III nitride buffer layers, and wherein the composition of the second set of regions is similar to a composition of a group III nitride buffer layer in the set of group III nitride buffer layers in the substrate structure.

A heterostructure comprising:

• a substrate structure including:
• a substrate;
• and
• a set of group III nitride buffer layers directly adjacent to the substrate;
• a set of group III nitride device layers located adjacent to the substrate structure;
• and
• a sacrificial layer located between the substrate structure and the set of group III nitride device layers, wherein the sacrificial layer includes an essentially continuous sublayer located directly adjacent to the set of group III nitride device layers and a non-continuous sublayer located directly adjacent to the set of group III nitride buffer layers, wherein the non-continuous sublayer includes plurality of columnar structures formed of a semiconductor material and a set of vacancies located laterally adjacent to the plurality of columnar structures.