Wednesday, June 06, 2007

US Patent 7227173 - LED with quantum dot/quantum well coupling

Quantum wells are thin films that create a two-dimensional barrier structure that confine electrons and are useful in a variety of applications including lasers and photodetectors. Quantum dots are structures which further confine electrons into zero dimensions. While quantum well based optoelectronic devices are fairly well established, there is a desire to use quantum dots to improve efficiency. However, it is difficult to achieve the necessary uniformity of size and sufficient distribution density to use quantum dot layers effectively. This patent proposes using adjacent quantum wells to create a bridge to facilitate the electron transfer between quantum dots. Claim 2 is representative.

2. A semiconductor device, comprising: a plurality of semiconductor layers; means for coupling signals to and/or from semiconductor layers of said semiconductor device; and a layer of doped quantum dots, comprised of III-V semiconductor material, disposed in at least one of said semiconductor layers as a source of carriers that communicate in either direction between said doped quantum dots and another layer.