Analysis of notch-δ-doped GaAs-based Gunn diodes

Abstract

The performances of GaAs-based Gunn diodes with a notch-δ-doped structure have been studied in this work. The δ-doped effect has been analysed using Monte Carlo modelling in terms of temporal evolution of current density, electric field profile, electron energy, mean velocity, and occupancy in Γ and higher valleys. The presence of a δ-doped layer after the notch caused a significant increase in the harmonic current amplitude of the device, where the growth of high field domain can be attributed to a slow electron track due to the well-known Gunn effect and an additional fast electron track which appears over a short time window when the domain is reaching the anode. An optimised GaAs notch-δ-doped structure with 700 nm device length including 100 nm notch and 5 nm δ-doped layer can generate signals at fundamental frequency of 262 GHz with a current harmonic amplitude of 29.4×107 A/m2, which is almost twice of that without δ-doped layer. Its second and third harmonic signals are found substantial reaching into the THz range of 512 GHz and 769 GHz.

Enhanced InP-based Gunn Diodes with Notch-d-doped Structure for Low-THz Applications

“…This increment can be attributed to the δ-doped effect on the performance of the InP Gunn diode. The presence of the δ-doped layer helps in modifying the electric field profile within the device which resulted in the increment of the electron energy, mean velocity, electron occupancy in the higher valleys and current density as well as reducing the dead zone at the beginning of the transit region as analysed in [11]. Thus, generating a better Gunn diode performance as compared to the conventional vertical Gunn diode structure.…”

“…8×10 16 cm −3 . The optimised GaAs notch-δ-doped Gunn diode is capable of operating at a fundamental frequency of 262 GHz with 2.94×10 8 A/m 2 under a DC bias of 2 V [11]. It is important to note that although the GaAs Gunn diode is shorter in length, its operating fundamental frequency is lower than that of InP 800 nm Gunn diode.…”

AlGaN/GaN bilateral IMPATT device by two-dimensional electron gas for terahertz application

“…However, the operating frequency of the Gunn diode is generally higher than that of the IMPATT diode for the same device size. The Monte Carlo model predicts a GaN Gunn diode with a transit length of 500 nm capable of operating at frequencies up to 625 GHz with an estimated output power of 3.0 W. 44 Akhbar et al 45 proposed GaAs-based Gunn diodes with notch-δ-doped structures, which produces a current harmonic amplitude of 29.4 × 10 7 A/m 2 at a fundamental frequency of 262 GHz. Its second and third harmonic signals reach 512 and 769 GHz, respectively.…”

Power-frequency performance of step-graded double Gunn diodes

“…The launcher is designed to be wide enough to resist low-energy tunneling but narrow enough to limit resistance. The doping spike following the launcher is required to achieve the desired electrical field in the transit region and avoid the development of a depletion region in the transit region [5], [6] [7] [8]. The transit region lengths and doping concentrations that were used to observe the double Gunn effect are listed in table 1.…”