Micro-cavity surface emitting Gunn laser

We demonstrate the pulsed operation of mono-polar GaAs Fabry-Perot (F-P) cavity and vertical cavity surface emitting (VCSEL) Gunn lasers. Both the F-P device and VCSEL are grown by metal-organic chemical vapour deposition (MOCVD) on semi-insulating GaAs substrates. The F-P device consists of n = 4.6 times 10¹⁷ cm^-3 doped GaAs active layer sandwiched between the Al_xGa_1-xAs(x = 0.32) wave-guiding layers (WG) or in the reference sample without the WG layers. The VCSEL device consists of an 2500 Aring thick, n = 5.0 times 10¹⁷cm^-3 dopes GaAs active layer sandwiched between the undoped distributed Bragg reflectors (DBR) at the bottom and the top. The operation of the devices is based on the band to band recombination of impact-ionized non-equilibrium electronhole pairs in the propagating high field domains in the Gunn diode, which is biased above the threshold of negative differential resistance and placed in either the Fabry-Perot or the vertical micro cavity. The current flow is longitudinally along the n-doped GaAs active layer. Therefore, vertical current injection through the high resistance reflector stack that is present in conventional vertical cavity surface emitting lasers (VCSELs) is avoided. Furthermore the device does not require ring contacts and the light emission occurs from the entire surface between the electrodes. Lasing from the devices is observed at temperatures between T ~95 and 300 K. Current voltage (I-V), light intensity vs. applied electric field (L-F) characteristics together with the lasing spectra are reported in this paper at T > 95 K.