Electrically Driven Nanocrystal Emitters Proposed

Daniel S. Burgess

Scientists at Los Alamos National Laboratory in Los Alamos, N.M., and at Sandia National Laboratories in Albuquerque, N.M., have reported a scheme that may be suitable for the electrical pumping of displays, light sources, optical amplifiers and lasers based on semiconductor nanocrystals.

Nanocrystal quantum dots are attractive for use in various emitters because their emission wavelength is dependent on their physical size, not the material on which they are based. An obstacle to the fabrication of practical devices, however, has been the lack of an efficient means of electrically pumping the dots.

In the work, the researchers describe an indirect technique by which unbound electron-hole pairs generated in a quantum well are transferred to a nearby quantum dot. To demonstrate the approach, they used a Ti:sapphire laser to optically excite InGaN quantum wells, which passed on their energy through a GaN layer to CdSe/ZnS nanocrystal quantum dots capped with organic molecules.

The findings suggest the scheme would work as well with electrically pumped quantum wells. Such an emitter, which the researchers call an energy-transfer color-converter, would feature a structure similar to a standard InGaN LED.