Experimental Study of Spin-Lattice Relaxation Times in Arsenic-Doped Silicon

Abstract

Measurements of the spin-lattice relaxation times of arsenic donors in a doped silicon crystal at 8500 gauss and 1.3°K are reported. The relaxation times for the stable ${\mathrm{As}}^{75}$ were measured by using adiabatic fast-passage techniques to observe the relative amplitudes of the electron resonance signals as a function of time. The relaxation times for the radioactive ${\mathrm{As}}^{76}$ were measured by observing the formation and decay of the nuclear alignment. For the ${\mathrm{As}}^{75}$, of which there are 2.8×${10}^{16}$ atoms/${\mathrm{cm}}^3$, the direct electron relaxation time is 6.5±0.5 minutes and the relaxation time for simultaneous spin-flips of the nucleus and the electron is 4.7±1 minutes. For the ${\mathrm{As}}^{76}$, of which there are 3×${10}^{10}$ atoms/${\mathrm{cm}}^3$, the direct electron relaxation time is 4±2 minutes and the relaxation time for simultaneous spin-flips of the nucleus and the electron is ≥75 minutes.