Nano-cathodoluminescence enables the design of light emitting diodes with higher efficiencies

Gatan instruments 

Gatan cathodoluminescence (CL) products enable optically-coupled transmission electron microscopy (TEM) to reveal and correlate nanoscale structural, optical, and electronic properties of materials

Background

Modern blue or white light emitting diodes (LED) use multiple InGaN quantum wells (QW) with GaN quantum barriers (QB) between the QWs to confine carriers for high brightness devices. However, a key challenge to the development of higher efficiency LEDs is the presence of a polarization-induced electric field that renders the device less efficient as a result of the quantum confined Stark effect (QCSE), which also gives rise to a red-shift of the emission wavelength. It has been proposed that the internal electric field can be suppressed by silicon-doping the QBs, and thus improve device efficiency. In order to validate this, it is crucial to resolve the spectral properties of individual QWs.