Photoluminescence study of silicon donors inn-type modulation-doped GaAs/AlAs quantum wells

Excited states of donors bound toXvalleys in GaAs–AlAs type II structures

“…However, for the 1s state the photoluminescence measurements by Lee et al [10] revealed a binding energy of 104 meV for a large AlAs layer of 131Å which is in good agreement with our previously calculated binding energy of 97 meV for X 1s z and 102 meV for X 1s x,y indicating that for these measurements the CR effective masses represent more adequately the measured binding energies.…”

“…Since the successful growth of n-type Si-doped GaAsAlAs structures [7] the calculation of these binding energies have become important for the understanding of bistable shallow-deep silicon donors in GaAs-AlAs [8], silicon interdiffusion [9] and photoluminescence spectra such as obtained by Lee et al [10].…”

Tunneling throughX-valley-related impurity states in GaAs/AlAs resonant-tunneling diodes

“…The values are consistent with those reported in the literature. 17,27 The energy position of the second resonant state is about 60-70 meV, which can be explained by the quantization of the X xy -valley-related states in AlAs.…”

“…Impurity atoms can provide impurity-assisted tunneling current peaks at very low voltage because of the relatively small height of the ⌫-X barrier at the GaAs-AlAs interface, as well as the large binding energy of X-valley-related Si donor states in AlAs ͑about 100 meV͒. 17 It is well known that the degeneracy of the impurity states in semiconductors with X minima of the conduction band is partially canceled due to the so-called valley-orbit interaction. As was shown in Ref.…”

“…It is of particular importance that X-valley impurity-related tunneling channels can provide the current peaks at quite low voltage, since the energy difference between the bottoms of the ⌫ band in GaAs and the X band in AlAs is only 120 meV, 16 and the binding energy of X-valley-related impurities in AlAs is about 100 meV. 17 Below we will present experimental results and our theoretical model, which allows us to describe the observed lowvoltage features in the I(V) characteristics as a resonant tunneling current through the X-valley-related impurity states. Briefly speaking, there are two important facts proving our idea about the origin of the impurity states.…”