Buffer Layers Having Composite Structures

An optoelectronic or electronic device, comprising:

• a substrate;
• a basis buffer layer of a first material disposed above the substrate;
• and
• a plurality of composite buffer layers disposed above the basis buffer layer sequentially along a growth direction from the substrate to a last composite buffer layer of the plurality of composite buffer layers, each specific composite buffer layer except the last composite buffer layer including:
• a first buffer sublayer of the first material, and
• a second buffer sublayer of a second material disposed above the first buffer sublayer, the specific composite buffer layer having a thickness ratio that is a ratio of a thickness of the second buffer sublayer to a thickness of the first buffer sublayer;
• wherein the thickness ratios of the composite buffer layers increase along the growth direction.

A wafer for semiconductor-based optoelectronic or electronic devices, comprising:

• a substrate;
• a basis buffer layer of a first material disposed above the substrate;
• and
• a plurality of composite buffer layers disposed above the basis buffer layer sequentially along a growth direction from the substrate to a last composite buffer layer of the plurality of composite buffer layers, each composite buffer layer except the last composite buffer layer including:
• a first buffer sublayer of the first material, and
• a second buffer sublayer of a second material disposed above the first buffer sublayer;
• wherein lattice constants of the second buffer sublayers of the composite buffer layers increase along the growth direction.