Characteristics and applications of micro-pixelated GaN-based light emitting diodes on Si substrates

Using a GaN-based light emitting diode (LED) epitaxial structure grown on Si, individually addressable 10 x 10 micro-pixelated LED (mu LED) arrays with pixel diameters of 45 mu m and peak emission at similar to 470 nm have been demonstrated. The electrical and optical properties of these mu LEDs were compared with those of broad-area LEDs fabricated from the same epistructure. The mu LEDs can sustain a much higher current density, up to 6.6 kA/cm(2), before thermal rollover. Also, the fabricated mu LEDs show good pixel-to-pixel uniformity, which demonstrates potential for low-cost micro-displays. Furthermore, these mu LEDs demonstrate a high electrical-to-optical modulation bandwidth of up to similar to 270MHz and are suitable for visible light communication at data transmission rate up to 400 Mbit/s. The electrical-to-optical modulation bandwidth of the mu LEDs increases rapidly with injection currents less than similar to 6mA, temporarily saturates at injection currents of similar to 6 to similar to 35mA, and gradually increases again with injection currents up to 110mA. Carrier density dependent recombination processes are responsible for the bandwidth increase at low current, the resistance-capacitance product determines the modulation bandwidth in the saturation region, and self-heating, which changes series resistance of mu LEDs, may cause a further bandwidth increase at high current. (C) 2014 AIP Publishing LLC.