Abstract
Recent new multilayer structures and their device applications are reviewed. These new concepts allow one to radically modify the conventional energy band diagram of a pn junction and thus tailor the high field transport properties to an unprecedented degree (band‐gap engineering). This approach has been used to propose and implement a new class of avalanche photodiodes with enhanced ionization rates ratio and the solid state analog of a photomultiplier (staircase detector). Other device applications such as repeated velocity overshoot structures are also discussed.