Enhancement of light emission characteristic of a GaAs-based Gunn light emitting diode with a quasi-cavity

We report on a novel GaAs-based quasi-cavity enhanced Gunn light emitting diode (GLED) with a planar architecture operating at around 876 nm. GLED device was fabricated using an n-type GaAs epilayer with and without bottom 20 pairs of Al0.1Ga0.9As/AlAs distributed Bragg reflectors (DBRs) to investigate the influence of the incorporated bottom DBRs on emission characteristic of the Gunn device. The devices start emitting when Gunn oscillations with a frequency of 1 GHz emerges at the negative differential resistance (NDR) threshold at 3 kV/cm. Light intensity-electric field characteristic of both GLEDs with and without DBRs shows an abrupt increase in emitted light intensity at NDR threshold. The full-width at half maximum (FWHM) of the electroluminescence (EL) spectrum is reduced from 30 nm to 14 nm, and emitted light intensity is enhanced by about four times of magnitude compared with the GaAs-GLED without a quasi-cavity. The period of Gunn oscillations is found to be 1ns (f = 1 GHz). Divergence of the emitted light from GaAs-GLED with a quasi-cavity is found to be lower than that from basic GaAs-GLED device. EL mapping images prove that as increasing applied electric field, EL intensity enhances and spans almost the whole sample surface with a higher intensity in the vicinity of the anode of the device as an indication of growing and propagating Gunn domain along the device. Our results reveal that the GLED with a quasi-cavity operates with a higher spectral purity. •GaAs-based Gunn light emitting diode (GLED) with and without quasi-cavity were investigated at room temperature.•The quasi cavity was demonstrated to increase the emission intensity by a factor of four and FWHM value was halved.•It was observed that the threshold electric field value is decreased in GaAs-GLED with a quasi-cavity.