Latest developments of HgCdTe e-APDs at CEA LETI-minatec

In this communication, we report on the electro-optical characterization of planar back-side-illuminated HgCdTe electron initiated avalanche photodiode (e-APD) test arrays with cut-off wavelengths lambda(c) = 2.4 mu m, lambda(c) = 4.8 mu m, and lambda(c) = 9.2 mu m. The e-APDs were manufactured at LETI using absorption layers grown by molecular beam epitaxy (MBE). We present measurements of the distributions in gain, noise, and equivalent input dark current. The mid-wave (MW) diodes yielded a very low dispersion (2%) and high operability (98%) for gains up to M = 200. The excess noise factor and equivalent input current (I-eq_in) operability were slightly lower, due to defects in the depletion region. The lowest measured value of I-eq_in = 1 fA corresponds to the lowest level measured so far in HgCdTe e-APDs and opens the way to new applications. The gain in the long-wave (LW) diodes was limited by tunnelling currents to a value of M = 2.4, associated with an average noise factor F = 1.2. A gain of M = 20 at a bias of -22.5 V was demonstrated in the short-wave (SW) e-APDs.