Influence of Boundary Conditions on High-Field Domains in Gunn Diodes

Böer, Karl W.; Döhler, G. H.

doi:10.1103/physrev.186.793

Cited by 33 publications

(8 citation statements)

References 26 publications

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“…The shape of the current-field relation is thus typically of N-type and domain formation effects are likely to occur (see [45] for a general overview). The prototype of an extended device with N-shaped current-field relation is the Gunn diode which exhibits selfsustained current oscillation due to traveling field domains [160][161][162][163][164][165][166]. A similar behavior has been suggested for semiconductor superlattices [18,167], and oscillatory behavior has indeed been found experimentally in the last years [19,168] with frequencies over 100 GHz [20,169].…”

Section: Formation Of Field Domainsmentioning

confidence: 63%

Semiconductor superlattices: a model system for nonlinear transport

2002

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Electric transport in semiconductor superlattices is dominated by pronounced negative differential conductivity. In this report the standard transport theories for superlattices, i.e. miniband conduction, Wannier-Stark-hopping, and sequential tunneling, are reviewed in detail. Their relation to each other is clarified by a comparison with a quantum transport model based on nonequilibrium Green functions. It is demonstrated how the occurrence of negative differential conductivity causes inhomogeneous electric field distributions, yielding either a characteristic sawtooth shape of the current-voltage characteristic or self-sustained current oscillations. An additional ac-voltage in the THz range is included in the theory as well. The results display absolute negative conductance, photon-assisted tunneling, the possibility of gain, and a negative tunneling capacitance. 2 Notation and list of symbolsThroughout this work we consider a superlattice, which is grown in the z direction. Vectors within the (x, y) plane parallel to the interfaces are denoted by bold face letters k, r, while vectors in 3 dimensional space are r, k, . . . . All sums and integrals extend from −∞ to ∞ if not stated otherwise.The following relations are frequently used in this work and are given here for easy reference:

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Section: Formation Of Field Domainsmentioning

confidence: 63%

Semiconductor superlattices: a model system for nonlinear transport

2002

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“…(2) The electron density at the electrode boundary must be low enough to fall into the over-linear decrease of conductivity (Schottky barrier condition). (3) The range between the first and second singular point must span a region in the forth quadrant of direction (this is not the case for the Gunn effect, hence here stationary domain cannot exist [18,28,[41][42][43]). (4) All external parameters must remain stationary.…”

Section: Figurementioning

confidence: 98%

“…Soon thereafter a large number of publications started to broaden the field with many theoretical and experimental investigations of the high-field domains [9][10][11][12][13][14][15][16], and separately of the Franz-Keldysh effect. Except for the further analysis of the stationary high-field domains by the research team of the author [17][18][19][20], the moving domains were almost exclusively analyzed by many other groups [21][22][23][24]. They are more easily observed by the kinetic behavior of the current either by periodic oscillations or by different forms of non-organized fluctuations [25].…”

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confidence: 99%

Stationary high‐field domains as tools to measure field‐dependent carrier densities and mobilities in CdS and work functions of blocking contacts

Böer

2012

Physica Status Solidi (b)

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It is shown that stationary high-field domains that occur in the range of negative differential conductivity, can be used to clearly identify field-quenched states in CdS. These are distinguished as cathode and anode-adjacent domains and permit an unambiguous determination of electron density and mobility as function of the electric field. The anode-adjacent domain permits additional insight into the high-field properties of CdS in a field range that is now stabilized in the prebreakdown range. Here one finds direct evidence, by using the spectral distribution of the photoconductivity within the domain, of inverting the CdS to p-type either by more complete quenching or by hole injection from the anode. Both types of stationary domains are determined by the work function of blocking contacts and thereby permit a closer analysis of the contact/CdS interface by shifting the space charge region away from the cathode to the bulk-side end of the domain. This allows a more precise determination of the dependence of the work function on the photoconductivity of the adjacent CdS. The field-of-direction (phase portrait) analysis of the time-independent transport and Poisson equations allows a simple classification of the two types of stationary high-field domains relating to the two singular points in the decreasing branch of the current-voltage characteristic. This permits a transparent discussion of the field distribution of these domains that can be directly observed by the Franz-Keldysh effect. Herewith the transition between cathode-to anode-adjacent domains as a function of the applied voltage can be directly followed.

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“…Thus, once the starting point is fixed (from boundary conditions [14,151) and the behavior of the %(X) and nz(X) curves and their intersections are determined for different values of r , the solution can be uniquely traced out, point for point through r using this modified form of the field of directions technique.…”

Section: ( 5 )mentioning

confidence: 99%

High-field domain solutions in a radial geometry

Hadley

Böer

Tyagi

et al. 1972

Phys. Stat. Sol. (a)

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A method of describing the behavior of high‐field domain solutions to the Poisson and transport equations for a radial geometry has been presented. This method is based on the field of directions techniques in a modified (n, r, F) space, and is applicable to materials exhibiting negative differential conductivity. The case of a small blocking cathode (e.g. point contacts) has been described for CdS as an example.

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Influence of Boundary Conditions on High-Field Domains in Gunn Diodes

Cited by 33 publications

References 26 publications

Semiconductor superlattices: a model system for nonlinear transport

Semiconductor superlattices: a model system for nonlinear transport

Stationary high‐field domains as tools to measure field‐dependent carrier densities and mobilities in CdS and work functions of blocking contacts

High-field domain solutions in a radial geometry

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