Potential Well Barrier Research Articles

Hot electron effects on the operation of potential well barrier diodes

A study has just been carried out on hot electron effects in GaAs/Al0.3Ga0.7As potential well barrier (PWB) diodes using both Monte Carlo (MC) and drift-diffusion (DD) models of charge transport. We show the operation and behaviour of the diode in terms of electric field, mean electron velocity and potential, mean energy of electrons and Γ-valley population. The MC model predicts lower currents flowing through the diode due to back scattering at anode (collector) and carrier heating at higher bias. At a bias of 1.0 V, the current density obtained from experimental result, MC and DD simulation models are 1.35, 1.12 and 1.77 μA/μm2 respectively. The reduction in current over conventional model, is compensated to a certain extent because less charge settles in the potential well and so the barrier is slightly reduced. The DD model results in higher currents under the same bias and conditions. However, at very low bias specifically, up to 0.3 V without any carrier heating effects, the DD and MC models look pretty similar as experimental results. The significant differences observed in the I–V characteristics of the DD and MC models at higher biases confirm the importance of energy transport when considering these devices.

Investigating the Role of Band Offset on the Property and Operation of the Potential Well Barrier Diodes

The impact of grading the GaAs/AlGaAs interface on carrier dynamics in a potential well barrier (PWB) diode has been explored and demonstrated in this paper. Three heterostructures in the GaAs/AlGaAs system namely GaAs/Al0.2Ga0.8As, GaAs/Al0.3Ga0.7As, and GaAs/Al0.4Ga0.6As with corresponding band offsets of 0.10, 0.25, and 0.30 eV, respectively, are investigated using the drift‐diffusion (DD) and Monte Carlo (MC) models. The behavior of the diodes with different band offsets are compared in terms of mean electron velocity, mean electron energy, and density of charge along the intrinsic regions and in the potential well. The MC simulation model enables the effects of space‐charge injection and carrier heating, which are not included in previous study of these structures, be treated quantitatively. Significant differences exist in the behavior of the three heterojunctions as this impacts the curvature coefficient and ideality factor of the diode. Both the ideality factor and curvature coefficient reflect the magnitude of band offset of the heterojunctions (interface).

Comparative Study of Heterostructure Barrier Diodes in the GaAs/AlGaAs System

A comparative study of the electron transport property and operation of the Potential Well Barrier (PWB) diode and Planar-doped Potential-well Barrier (PPB) diode has been carried out in this study. Both diodes are heterostructures in GaAs/AlGaAs system with similarities in layer design though, with a sheet charge inserted close to the well of the PPB diode. A drift-diffusion and Monte Carlo simulation models were used throughout the study to examine the behavior of electrons in terms of the electric field distribution across the diodes, electron velocities, electron energy and densities. Results of simulation has shown how the electric field varies in the left and right intrinsic regions of the device and the effect of the field on velocity. The I-V characteristics of the experimental and simulation results have shown a good agreement in the two diodes though, with little adjustment of about ± 2.5% to design parameters in order to obtain a good fit with experimental results. The I-V characteristics of the diodes reveal that the PPB diode turns on at a higher voltage than the PWB diode though, with a better asymmetry in the reverse bias operation. This is because the sheet charge in the PPB diode produces additional charge and together with the charge in the well, presents a higher potential barrier than the PWB diode whose barrier is determined by the charge in the well only. The diodes demonstrate promising RF behavior with voltage responsivity of 10900V/W and 6400V/W at 10GH for the PPB and PWB diodes respectively.

Investigating effect of temperature on barrier height of PWB diodes

The effect of temperature on the barrier height of a gallium arsenide (GaAs)/aluminium GaAs (AlGaAs) potential-well barrier (PWB) diodes is investigated and reported in this Letter. It was found that more electrons diffuse from the doped AlGaAs(silicon) into the undoped layers with increasing temperature, this modifies the electric field along these layers and hence the barrier height. The barrier height increases with increasing temperature at an increasing rate of 0.093 – 0.36 meV / K in the temperature range of 200–380 K in a similar way to the planar-doped barrier (PDB) diode. The result of the computer simulations, however, shows that the PWB diode is less sensitive than the PDB diode due to the active nature of the charge in the well.

GaAs/AlGaAs potential well barrier diodes: Novel diode for detector and mixer applications

Heterostructure potential well barrier (PWB) diodes in GaAs/AlGaAs system operating in a similar way to Planar Doped Barrier (PDB) diodes, though exploiting a potential well to trap charge, rather than a fixed doping spike have recently been realized and reported in the literature. This paper analyses the complex operation of these devices and determines the sensitivity of the current–voltage (I–V) characteristics to various design parameters. The PWB diode displays a significant temperature sensitivity, opposite in nature to PDB temperature dependence, and this suggests the possibility of temperature stabilised hybrid designs. The active bias dependence nature of charge within the well is found to have a significant effect on the device and impacts the ideality factor, which is more bias dependent than other comparable devices such as PDBs. However, the same mechanism offers the prospect of improvement in the current asymmetry and this effect can be greatly improved upon by changing the design and shape of the potential well.

Potential Well Barrier Diodes for Submillimeter Wave and High-Frequency Applications

A GaAs-based potential well barrier (PWB) diode having a $n^{++}-i-n^{++}$ epitaxial structure has been successfully designed and demonstrated. The diode uses a GaAs potential well inserted between two intrinsic AlGaAs regions in which charges accumulate to form a barrier. The device is similar in operation to a planar doped barrier diode. Results of simulations have shown good agreement with an experiment and a promising asymmetric behavior in the I–V characteristics as well as a low turn-ON voltage capability. The asymmetric structures of the PWB diode can be controlled by varying the lengths of intrinsic regions and the size and depth of the well. Simulation results using drift-diffusion and Monte Carlo models demonstrate that charge in the well is a function of bias in such a way as a higher barrier exists in reverse bias than in forward. The active nature of this variation offers potential improvements over PDB structures where the charge is defined by doping. The diode demonstrates promising RF signal detection capability with a voltage responsivity of 6.4 mV/ $\mu \text{W}$ at 10 GHz. Such a potential well-tailored diode can find exciting applications in zero bias detectors.