In order to study the energy spectrum of shallow donor confined in volcano-shaped InAs/GaAs QR, taking into account strong nonparabolicity of the InAs conduction band
, we use below a simple version of the Kane model, proposed in [23, 24].
The energy level above the Fermi surface (0 eV) is the conduction band
, and the energy level below the Fermi surface is the valence band.
From this state, the electron is injected into the conduction band
of the semiconductor oxide, generating a dye cation ([S.sup.+]).
Furthermore, the superoxide anions are also formed by the molecular reduction of O2, which may take place by the presence of electrons in the conduction band
at the surface of the photocatalyst (4).
In Figure 3, a sharp increase in the absorption at 2.72.8 eV is observed in the absorption spectrum of the sample doped with boron, which is associated with transitions from the boron levels to the conduction band
. A sharp yield to saturation indirectly confirms our data obtained by electrophysical measurements on a significant boron concentration up to 1020 [cm.sup.-3] .
As shown in Figure 1, when a photon with adequate energy (>bandgap energy of semiconductor) is absorbed by the semiconductor, an electron from valence band (VB) gets excited and jumps to the conduction band
(CB), which generates a hole in the valence band.
where [K.sub.b] is Boltzmann's constant, T is temperature, [N.sub.c] is effective density of states (DOS) for electrons in conduction band
, [N.sub.v] is effective density of states (DOS) for holes in valence band, and [E.sub.F], [E.sub.c,eff], and [E.sub.v,eff] represent fermi level, conduction band
edge, and valence band edge, respectively.
Alternatively, metal decoration of Ti[O.sub.2] photoanodes by tailoring photoanode properties, redistributing defects, and trapping levels in the band gap enables changing the conduction band
where the integral is over the unit cell, summation over all initial valence band and conduction band
states of allowed ones, and [M.sub.if] is the momentum matrix elements for interband transitions.
However, if there are many of these sub-band gap states, the electrons in the conduction band
can move slowly back down to the valence band.
(27) [Fe.sup.3+] impurity level formed under the conduction band
(CB) induces the high photocatalytic activities of iron-doped Ti[O.sub.2].
Examining the states at valence band edge, the orbital contributions are mainly from the 2p orbitals on the nitrogen atoms, while the conduction band
is narrow with contributions mainly from 4p orbitals on the gallium atoms.