Minority carrier lifetime and radiation damage coefficients of germanium

We report on the measurement of minority carrier lifetime and on the radiation damage resistance of bulk Ge. Lifetime measurements are performed using the resonance-coupled photoconductive decay (RCPCD) method. Specifically, we examine the dependence of the lifetime as a function of the Ge resistivity and various 1 MeV electron radiation fluences. We measure hole lifetimes ranging from ∼0.9-34 μs for n-type Ge samples, corresponding to diffusion lengths of ∼30-400 μm. Electron lifetimes in p-type Ge range from ∼0.6-19 μs, corresponding to diffusion lengths of ∼30-420 μm. Lifetime measurements are also made after exposure to 1 MeV electron fluences ranging from 10¹³ to 10¹⁵ cm^-2 and these results are used to estimate the minority carrier lifetime and diffusion length damage coefficients K_τ and K_L.