Energy and Frequency Properties of Planar n+-n-n+ Diodes with Active Side Boundary

Authors O.V. Botsula , V.O. Zozulia

V.N. Karazin Kharkiv National University, 4, Svoboda Sq., 61077 Kharkiv, Ukraine

Issue Volume 13, Year 2021, Number 6
Dates Received 10 October 2021; revised manuscript received 17 December 2021; published online 20 December 2021
Citation O.V. Botsula, V.O. Zozulia, J. Nano- Electron. Phys. 13 No 6, 06028 (2021)
PACS Number(s) 85.30.Fg, 73.40.Kp, 73.40. – c
Keywords Active side boundary, Electric field strength, Impact ionization, Negative differential conductivity, Doping level, Frequency range, Generation efficiency (2) .

Generation of electromagnetic oscillations in the long-wavelength part of the terahertz range by GaAs diodes is investigated. Diodes are planar structures with a length of 1.28 μm, a width of 0.32 μm and a concentration of donor impurity of 6·1022 m – 3. Diodes include a conductive channel placed on a semi-insulating substrate, two contacts and an active side boundary in the form of an n-type region located between the channel and the metal electrode electrically connected to the ohmic contact of the anode. Electronic processes in the structure are analyzed by means of Ensemble Monte Carlo method. Current instabilities occurring in such a diode connected with the effect of inter-valley electron transfer are shown up. Dependences of direct current on voltage do not have a pronounced region with negative differential conductivity, which may be due to the existence of regions with high electric field strength in the anode part of the diode. Our research reveals that the simultaneous existence of the effect of interval valley electron transfer in the channel and in the region of lateral boundary leads to an increase in the frequency of oscillations and an expansion of the frequency range. Oscillation efficiency and frequency properties of the diodes are determined. The frequency range of diodes is established to be in the range from 100 to 300 GHz. The maximum generation efficiency is about 3 % at a frequency of 160-180 GHz. The influence of the position and size of the elements forming the active side boundary on the frequency and energy properties of diodes is explored. The operating frequency range of diodes is shown to be determined mostly by the thickness of the side boundary element. The maximum oscillation frequency (up to 300 GHz) and frequency bandwidth are obtained for diodes with a thickness of the side boundary element of 0.32 μm, but with the maximum efficiency of less than 1.4 %.

List of References