Integration Of Resonant Tunneling Diode Research Articles

Delayed Feedback Dynamics of Liénard-Type Resonant Tunneling-Photo-Detector Optoelectronic Oscillators

We use the nonlinear dynamics approach for studying delayed feedback optoelectronic oscillators (OEOs) formed by hybrid integration of resonant tunneling diode (RTD) photo-detectors with laser diodes, in both single and dual optical fiber feedback routes. In the single loop topology, the performance of the RTD-OEO free-running self-sustained oscillator is improved in terms of phase noise, with a compromise between the delay line and the strength of the optical re-injection. In the dual-loop configuration, superior performance is achieved due to the suppression of the side modes associated with the optical cavity length, resulting in a side mode suppression ratio of up to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${-}{\rm 60}~{\rm dBc}$</tex></formula> of the carrier frequency. We compare experimental results with numerical simulations based on a system of delay differential equations comprising a Liénard oscillator model driven by white Gaussian noise and coupled with laser rate equations. The delayed feedback Liénard oscillator model gives considerable insight into the RTD-OEO dynamical regimes predicting its main features in both single- and dual-loop configurations.

InP-based RTD/HEMT monolithic integration

Monolithic integration of resonant tunneling diodes (RTDs) and high electron mobility transistors (HEMTs) is an important development direction of ultra-high speed integrated circuit. A kind of top-RTD and bottom-HEMT material structure is epitaxied on InP substrate through molecular beam epitaxy. Based on wet chemical etching, metal lift-off and air bridge interconnection technology, RTD and HEMT are fabricated simultaneously. The peak-to-valley current ratio of RTD is 7.7 and the peak voltage is 0.33 V at room temperature. The pinch-off voltage is −0.5 V and the current gain cut-frequency is 30 GHz for a 1.0 μm gate length depletion mode HEMT. The two devices are conformable in current magnitude, which is suitable for the construction of various RTD/HEMT monolithic integration logic circuits.

Monolithic Integration of Resonant Tunneling Diodes, Schottky Barrier Diodes and 0.1-µm-gate High Electron Mobility Transistors for High-Speed ICs

Monolithic integration technology for resonant tunneling diodes (RTDs), Schottky barrier diodes (SBDs), and 0.1-µm-gate high electron mobility transistors (HEMTs) was developed. The integration process was investigated to overcome the difficulty in fabricating both RTDs with a mesa height of 530 nm and HEMTs with a gate length of 0.1 µm. The HEMT and SBD structures were grown by metalorganic chemical vapor deposition (MOCVD) on a 2-inch InP substrate. The RTD structure was regrown by molecular beam epitaxy (MBE) on the top layer grown by MOCVD. The characteristics of the fabricated devices showed good uniformity. An analog-to-digital converter and a selector circuit fabricated with these devices operated properly. The presented integration technology is a promising way to provide novel circuits with RTDs, SBDs and 0.1-µm-gate HEMTs.

Monolithic integration of resonant tunneling diodes and heterojunction bipolar transistors on patterned InP substrates

We report the successful fabrication of coplanar, monolithic integrated circuits based on heterojunction bipolar transistors (HBTs) and resonant tunneling diodes (RTDs). Molecular beam epitaxy growth of the integrated device structure is performed on an InP wafer, which is patterned by photolithography and dry etching prior to growth. The substrate pattern consists of pedestals, which support RTDs after postgrowth device fabrication, and a lower level which ultimately supports HBTs. In situ sensors for layer thickness (photoemission oscillations) and substrate temperature (absorption-edge spectroscopy) play a critical role in controlling key growth and structural parameters for the HBT and RTD devices. Utilization of the photoemission oscillation sensor during deposition of the AlAs barrier layers of the RTD structure has enabled control of peak currents to a design tolerance of ±20% for devices with current densities in the mid-104 A/cm2 range. Implementation of proportional–integral–derivative control based on a transmission-mode absorption-edge spectroscopy sensor has enabled regulation of the substrate temperature to a precision of ±1 °C throughout deposition of the RTD/HBT structure.

Monolithic integration of resonant tunneling diodes and FET's for monostable-bistable transition logic elements (MOBILE's)

A MOBILE (monostable-bistable transition logic element), employing two n-type negative differential resistance devices connected in series, is a functional logic gate with the advantages of multiple inputs and multiple functions. In this paper, a novel approach to achieve MOBILE operation is demonstrated using monolithic integration of resonant tunneling diodes (RTD) and FETs. In our new integration structure, an RTD and FET are connected in parallel. This structure offers several advantages including separate optimization of RTD's and FET's, and flexible circuit design abilities. For a single-input MOBILE gate, inverter operation at room temperature is demonstrated as the evidence of monostable-to-bistable transition.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Monostable-Bistable Transition Logic Elements (MOBILEs) Based on Monolithic Integration of Resonant Tunneling Diodes and FETs

A MOBILE (monostable-bistable transition logic element) is a functional logic gate employing two negative differential resistance devices connected in-series. This logic gate offers the advantages of multiple inputs and multiple functions. In this paper, a novel approach to achieving MOBILE operation is demonstrated based on monolithic integration of resonant tunneling diodes (RTDs) and field-effect transistors (FETs). In our new integrated structure, an RTD and FETs (one or more) are connected in-parallel. This structure offers several advantages including separate optimization of the RTDs and FETs, and flexible circuit design abilities. For a single-input MOBILE gate, inverter operation is demonstrated as an evidence of monostable-to-bistable transition. For a two-input gate, both NAND and NOR operation is achieved with different control voltages, which implies the possibility of a variable-function logic gate.

Theoretical investigations of a proposed series integration of resonant tunneling diodes for millimeter-wave power generation

The double-barrier quantum-well resonant tunneling diode (RTD) has great potential for power generation at millimeter-wave frequencies. If a number of RTDs are integrated in series, the integrated device can greatly increase the total output power and help remove the problem of low-frequency spurious oscillations associated with a single RTD. The feasibility of such a series integration scheme is investigated. The advanced monolithic nonlinear transmission line (NLTL) generating picosecond voltage shock waves can be used to initiate oscillation in such series-integrated RTDs to overcome the DC instability. The large-signal RF characteristics of the series-integrated RTDs are analyzed and simulated, including transit time effects in the depletion region. Available GaAs-AlAs RTD data was used to obtain computer simulation results showing that a total CW output power of about 0.1 W with a DC-to-RF conversion efficiency of about 8% can be generated to a 5- Omega load at 100 GHz, if ten such RTDs are integrated in series. >