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 ar-chitecture 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 in-crease in emitted light intensity at NDR threshold. The full-width at half maximum (FWHM) of the electrolu-minescence (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.