Electronic structure ofn-type δ-doping multiple layers and superlattices in silicon

Abstract

The electronic subband structure of periodically n-type b-doped silicon is calculated selfconsistently within the local-density approximation. Two types of energy levels are distinguished, one due to valleys transverse to the superlattice axis, and the other due to longitudinal valleys.Minibands, potential pro61es, miniband occupancies, and Fermi-level positions are studied and their dependence on the spacing d between b layers and the doping concentration ND is obtained.Pronounced changes with increasing ND and decreasing d are observed. For d ) 150 A, and 10 & N~& 10 cm, the system behaves as a set of practically independent isolated 8-doped wells. Significant dispersion of the higher subbands takes place for d lower than 150 A. . The transition from a multiple-b-doped-well behavior to a superlattice regime is observed for doping concentrations ) 2.0 x 10 cm and periods d ( 50 L. The twofold degeneracy of longitudinal levels and the fourfold degeneracy of tranverse levels are removed by the many-valley coupling. The corresponding splitting energies are calculated.

Electronic properties ofδ-doped Si:P and Ge:P layers in the high-density limit using a Thomas-Fermi method

“…where z is distance perpendicular to the δ-layer, ν is the number of equivalent conduction valleys, ǫ r is the static dielectric constant,m is the geometric average of the longitudinal (m l ) and transverse (m t ) effective masses 23,37,38,46 …”

On intersubband absorption of radiation in delta-doped QWs

“…Meanwhile an impurity delta doping technique was developed [12], which was followed by numerous researches of the delta layer properties. Given that the present article deals with delta doping in Si QW structures, the examples here mentioned describe delta doping in Si [13][14][15]. It worth noticing that impurity concentrations of those layers were usually taken so large that the tails of the density of states were formed within the forbidden gap and, consequently, all the impurities were considered as ionized even at the helium temperature.…”

Thomas-Fermi approximation inp-type δ-doped quantum wells of GaAs and Si

“…Work on ␦-doped structures was initially on n-type structures, and has allowed one to study the subband spectra and mobilities of these systems through electrical and optical measurements. [1][2][3][4] p-type ␦-doped GaAs quantum wells can be made with Be, Si-acceptor, and C layers. [5][6][7][8] They are suitable systems for the study of the physics at extremely high carrier densities, and for potential technological applications (␦-FET, 2,9,10 ALD-FET, 11 etc.͒.…”