Optical Determination of the Symmetry of the Ground States of Group-V Donors in Silicon

Excitation lines from the doublet, $1s\left(E\right)\mathrm{}$, and the triplet, $1s\left(T_1\right)$, states have been measured at temperatures ∼80, 59, and 30°K for P, As, and Sb donors in silicon. On the basis of the relative intensities of the lines with the same final state it is deduced that the $1s\left(E\right)\mathrm{}$ state lies above the $1s\left(T_1\right)$ state for all three impurities investigated. At ∼30°K the $1s\left(T_1\right)\to 2p_0, 2p_{\pm }$ transitions for antimony impurity resolved into a doublet. Uniaxial stress measurements for P and Sb, with compression F parallel to [100] or [110] and with the electric vector E either parallel or perpendicular to F, indicate that the lines with $1s\left(T_1\right)$ as their initial state do not exhibit any splittings or shift in their energies. On the other hand, the lines with $1s\left(E\right)\mathrm{}$ as their initial state exhibit splittings with dichroic features. Experimental observations of the number and the positions of the stress-induced components and their polarization characteristics are consistent with the ordering in which $1s\left(E\right)\mathrm{}$ lies above $1s\left(T_1\right)$.