CMOS-compatible light emission device based on thin aluminum nitride film containing Al nanocrystals

Aluminum nitride (AlN) films have attractive physical properties, such as wide bandgap (6.2 eV), high thermal conductivity (320 W/mK), and good match of both thermal expansion coefficient and lattice constant to those of Si substrate . Based on these properties, AlN films can be applied in surface acoustic wave (SAW) devices [1], memories devices [2], and optoelectronic devices [3]. It has been reported in our recent studies that amorphous AlN thin films containing aluminum nanocrystals (nc-Al) deposited on Si substrate by radio-frequency (rf) magnetron sputtering possess memory effect [2] and exhibit interesting current conduction behaviors [4]. In this work, strong visible electroluminescence (EL) from the nc-Al/AlN thin film is observed at room temperature. The film was deposited on p-type Si substrate by rf magnetron sputtering of a pure Al target in a gaseous mixture of Ar and N₂. To form the metal-insulator- semiconductor (MIS) light emitting structure, the sample surface was coated with an array of indium tin oxide (ITO) gate electrodes. A 200 nm Al was deposited on the wafer backside to serve as the bottom electrical contact.