Towards the fabrication of a UV light source based on CuCl thin films

Abstract

CuCl is an ionic wide band gap I-VII semiconductor which has a band gap of 3.4 eV (at 300 K) and a large excitonic binding energy of 190 meV compared to other wide band gap semiconductors, e.g. ZnO (60 meV) and GaN (25 meV). It can be useful as a UV source which can emit light in the blue-UV range. The large excitonic binding energy of CuCl should improve the quantum efficiency compared to ZnO or GaN. In room temperature UV-VIS spectroscopy measurements we have observed strong free Z 3 and Z 1,2 excitonic peaks in vacuum-deposited CuCl films incorporated within structures for electroluminescent devices. Using room temperature photoluminescence (PL) we have also observed a strong free excitonic peak which is attributed to Z 3. We also report on the design of a UV source using electrically pumped CuCl thin films on Si and ITO coated glass substrates. This could open up the possibility of fabricating UV/blue light emitters utilizing CuCl. © Springer Science+Business Media, LLC 2007.