InGaAs-based Graded Gap Active Elements with Static Cathode Domain for Terahertz Range

Authors O.V. Botsula , K.H. Prykhodko , V.A. Zozulia

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

Issue Volume 11, Year 2019, Number 1
Dates Received 03 December 2018; revised manuscript received 06 February 2019; published online 25 February 2019
Citation O.V. Botsula, K.H. Prykhodko, V.A. Zozulia, J. Nano- Electron. Phys. 11 No 1, 01006 (2019)
PACS Number(s) 85.30.Fg, 73.40.Kp, 73.40. – c
Keywords Diodes (4) , Impact ionization, Graded gap layer, Domain (10) , Electric field strength, Compound composition.

Terahertz radiometric systems, two-dimensional visualization systems, terahertz tomography and spectroscopy, etc. need noise sources at frequencies above 100 GHz. Frequency capabilities of commonly used elements are limited. Diodes with a static cathode domain or DCSD are known to be noise sources in mentioned ranges as well. Due to low doping, DCSD can be considered as perspective active elements for an ultra-high frequency application. The paper describes InGaAs-based graded-gap active diode elements with a static cathode domain. They have structure of n+-n–-n-n+ types and length about 1 (m, where n– is a low doping level region with 0.3-0.5 (m thick. Diodes are considered to be active elements for both generating noise and electromagnetic current oscillations. The working principle of diodes is impact ionization in static domain of a strong electric field in cathode. The results of modeling by using the ensemble Monte Carlo method are presented. Possibility of noise generation in the range from 100 to 500 GHz is shown. Power spectral density of noise was determined in important specific areas of the electromagnetic spectrum which corresponds to atmospheric windows. The influence of doping levels and gallium fraction on GaInAs region of cathode contact is considered.Current oscillations generation in the range of 100-200 GHz is found. The estimations of generation efficiency are given. Maximum efficiency corresponds to a frequency of about 130 GHz and its value of 1-2 % is obtained. Frequency oscillation limit of the diode exceeds 180 GHz. Considered regime is similar to limit space charge accumulation mode.

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