Excitation Spectra of Donors in Aluminum Antimonide

The photoexcitation spectra associated with tellurium and selenium donors in aluminum antimonide have been studied. At liquid-helium temperatures, sharp lines are observed in the spectra associated with both donors. At liquid-nitrogen temperature, the lines of the tellurium spectrum broaden, whereas those of selenium vanish, being replaced by a broad region of continuous high absorption. For both tellurium and selenium donors, none of the above features are observed at 300^∘{}K. In each case, at photon energies higher than the donor ionization energy, absorption peaks have been observed which are consistent with their arising from electronic transitions accompanied by the emission of phonons. The effect of uniaxial stress has been studied for the excitation spectrum of both donors. On the basis of the absence of splittings of the selenium lines for compressive force F parallel to $〈111〉$, it is deduced that the conduction-band minima occur along $〈100〉$. On the basis of the number of stress-induced components and their dichroic properties, it is concluded that line 1 of the tellurium donor at 38.31 meV and line 1 of the selenium donor at 117.13 meV are due to a 1s(A₁)→1s(T₁) transition. Similarly, line 2 of the tellurium donor at 57.96 meV and line 2 of the selenium donor at 134.3 meV have been attributed to a 1s(A₁)→2p₀ transition.