Defect dominated conductivity in Zn 3P 2

Abstract

The electrical resistivity and Hall coefficient of Zn 3P 2 have been measured for single crystal and thin polycrystalline film samples which were annealed over a range of equilibrium vapor compositions and temperatures. The room temperature electrical resistivity of single crystal samples annealed at 573 K varied from approximately 10 5Ω-cm for single crystals heated in equilibrium with zinc to 10 Ω-cm for those annealed in a phosphorus rich ambient. Hall measurements indicate that a variation in carrier concentration is responsible for these changes. The experimentally observed dependence of carrier concentration [ h° ], (cm −3) on phosphorus pressure is given by [ h°] = 1.32 · 10 16 [ p(P 4)] 0.13 for samples annealed at 573 K. The experimentally determined pressure dependence is in good agreement with a model based on phosphorus interstitials acting as acceptors. The pressure and temperature dependence of the carrier concentration yield the equilibrium constant K I for the formation of interstitial phosphorus defects according to the reaction 1 4 P 4 → P′ i + h° where K I = 10 42.4 ± 2 cm −6 torr 0.25[p(P 4)] −0.25 exp(−1.18 ev kT ) . The accommodation of phosphorus interstitials is discussed in light of the crystal structure of Zn 3P 2.