Gunn oscillations in planar heterostructure diodes

Abstract

Gunn oscillations have been observed and modelled, using a Monte Carlo method, in planar semiconductor GaAs/AlGaAs heterostructure diodes. Our simulation results support an interpretation of experimental results whereby the Gunn domains travel parallel to the semiconductor layers, as opposed to perpendicular to the layers in traditional vertical devices. Fabricated devices with contact separations of 4 µm down to 1.3 µm have been found to oscillate over a range of frequencies from 24.5 GHz to 108 GHz. These structures offer the prospect of generating frequencies further into the terahertz range and an increased ease of integration and flexibility over equivalent traditional vertical structures.

Terahertz oscillations in an In0.53Ga0.47As submicron planar Gunn diode

“…Simulations of GaAs based planar Gunn diodes such as those reported in [28][29][30] showed a similar natural limit in size with devices shorter than 0.7 µm struggling to operate. Better results were obtained from the InGaAs structure.…”

“…The accumulation layers formed a little closer to the anode than cathode (about mid way) and grew in size as they transferred from the cathode to anode at the saturation velocity. The resulting frequency was well approximated by f = 2.25×10 5 /Lac Hz (a little over twice the saturation drift velocity of about 0.9×10 5 ms -1 in GaAs and 1.1×10 5 ms -1 at 1x10 6 Vm -1 in InGaAs [31]) over the distance between anode and cathode Lac) [8,17]. Higher biases were needed in the simulation to maintain accumulation layer oscillations as Lac was decreased.…”

“…Published work with planar Gunn diodes has demonstrated that operation frequencies of up to 110 GHz are possible [17] in GaAs and at over 160 GHz in In0.53Ga0.47As for 1.3 μm long devices [18]. In recent years, planar Gunn diodes have shown consistent improvements in frequency towards the THz region of electromagnetic spectrum [3].…”

Impact ionisation electroluminescence in planar GaAs-based heterostructure Gunn diodes: Spatial distribution and impact of doping non-uniformities

“…This device design would potentially result in reduced heat generation and would also allow for improved heat extraction prospects when compared to the conventional vertical design 1,2 . Planar GaAs…”

Influence of absorber layer dopants on performance of Ge/Si single photon avalanche diodes

“…The charge transport model chosen follows an established Monte Carlo approach 18 , our implementation of which we have developed and applied over a number of years [19][20][21][22] and now extended to Ge. Since the SPAD operates in a heavily reverse-biased mode and is essentially depleted of mobile charge except during avalanche, only electron transport is included because the device relies upon these carriers for avalanche triggering in the Si layers.…”