J. J. Quinn

Subband spectroscopy by surface channel tunneling

Abstract Surface channel tunnel junctions (SCTJ) can be fabricated by replacing the usual degenerate n-type source contact on a weakly p-type substrate by a highly degenerate p-type source. In the presence of a gate voltage strong enough to produce a surface inversion layer, a tunnel junction connecting the three-dimensional p + source and the quasi-two-dimensional n-type surface channel can occur. The I - V characteristics of this SCTJ will yield valuable information about the subband splittings and other electronic properties of the surface inversion layer.

Magnetoplasma modes of a spatially periodic two-dimensional electron gas

Abstract We examine the magnetoplasma dispersion of a two-dimensional electron gas with a spatially periodic charge density. The system studied is a periodic array of two-dimensional electron gas strips with constant equilibrium density. The integral equation describing the charge fluctuations on the strips, has been derived and solved numerically. The spatial dependence of the form of either propagating or evanescent waves. The latter are associated with the edge modes, recently discovered in electrons on liquid4 He. For a periodic array of two-dimensional strips, the modes in different strips, interact and form bands.

Polariton modes of semiconductor superlattice systems

Abstract The general dispersion relation for polariton modes of a system described by a spatially periodic local dielectric function is derived. The dispersion relation is evaluated numerically for a number of different semiconductor superlattice systems.

Theory of surface plasmon polaritons in truncated superlattices

Abstract A theoretical investigation has been made of surface plasmon polariton modes in truncated superlattices using a local theory with retardation. The modes are characterized by electric fields that decay exponentially away from each interface and that have an envelope that decays exponentially away from the end of the truncated superlattice. A criterion for the existence of the surface models is developed. Numerical results are presented for several illustrative cases.

Magnetic polaron effects in CdTeCd1−xMnxTe quantum well systems

Abstract The magnetic polaron effect resulting from the exchange interaction between an electron or a hole in a CdTe Cd 1− x Mn x Te quantum well and the localized Mn-ion spins is studied theoretically. The non-linear nature of the effective Schrodinger equation for the carrier can lead, under appropriate conditions, to its localization near one of the quantum well interfaces.

Helicon waves in semiconductor superlattices

Abstract The dispersion relation for the helicon frequency of a system consisting of a periodic array of two-dimensional gas layers is studied as a function of both q and qz, the components of the wavevector parallel and perpendicular to the layers. The result is compared with that for a homogeneous three-dimensional electron gas.

Intrasubband plasma modes of a semi-infinite superlattice: A new type of surface wave☆

Dispersion relations are derived for the bulk and surface plasma modes of a model semi-infinite superlattice. The model consists of a periodic array of two-dimensional electron layers embedded in a material of dielectric constant ϵs terminating at the interface with a homogeneous medium of dielectric constant ϵ0. The bulk modes form a continuum, and the surface mode, which exists only for wavelengths shorter than a critical value, can occur either above or below the bulk continuum depending on the ratio of ϵs to ϵ0.

Electron-electron interactions in the surface inversion layer of a semiconductor

Abstract The effective unscreened interaction between a pair of electrons in the inversion layer of an MIS structure is estimated by using classical electrostatics together with a knowledge of the quantum mechanical wave function of the inversion layer electrons. The change in the effective mass m ∗ and effective g-value g∗ are evaluated in the random phase approximation.

Amplification of bulk and surface plasmons in semiconductor superlattices

We study the amplification of bulk and surface plasmons in a type II semiconductor superlattice, which consists of a semi‐infinite array of spatially separated electron and hole layers. Amplification is achieved by imposing an external drift velocity on the electrons. For drift velocities exceeding a threshold value, bulk plasmons can be amplified for an arbitrary plasmon wave vector parallel to the layers. Amplification of surface plasmons can occur only for finite wave vectors. Drift velocities required for these processes are calculated and are shown to be experimentally feasible.

Collective modes of semiconducting space charge layers

A self-consistent energy functional perturbation theory is used to evaluate the linear response of the quasi-two-dimensional electron gas of a surface space charge layer or quantum well to an external perturbation with arbitrary space and time dependence. Collective modes of the system are determined from the poles of the appropriate response function. In the absence of a de magnetic field intersubhand collective modes as well as the usual two-dimensional plasmon with ωp(q)−(2πNinve2q/mϵs)12 are found. In the presence of a de magnetic field both spin waves spin independent excitations occur. One example of the latter is the hybrid magneloplasma waave with ω2 − ω2e + ω2p(q).