dc-Hydrogen plasma induced defects in bulk n-Ge

Abstract

Bulk antimony doped germanium (n-Ge) has been exposed to a dc-hydrogen plasma. Capacitance-voltage depth profiles revealed extensive near surface passivation of the shallow donors as evidenced by ˜ a 1.5 orders of magnitude reduction in the free carrier concentration up to depth of ˜ 3.2 µm. DLTS and Laplace-DLTS revealed a prominent electron trap 0.30 eV below the conduction (Ec-0.30 eV). The concentration of this trap increased with plasma exposure time. The depth profile for this defect suggested a uniform distribution up to 1.2 µm. Annealing studies show that this trap, attributed to a hydrogen-related complex, is stable up to 200 °C. Hole traps, or vacancy-antimony centers, common in this material after high energy particle irradiation, were not observed after plasma exposure, an indication that this process does not create Frenkel (V-I) pairs.