Current mechanisms and 1/f noise in 8-12 µm n+on p (Hg,Cd)Te photodiodes

Process improvements have enabled fabrication of boron-implanted 8-12µm n⁺on p Hg0.8Cd0.2Te junction photodiodes with reduced generation-recombination (G-R) current and 1/f noise. In this paper the current-voltage characteristic (I-V) is successfully modeled for the first time in (Hg,Cd)Te using the temperature dependence of diffusion and G-R currents. The photodiode area dependence indicates that the G-R current is surface in nature and described by a depletion surface recombination velocity, measured at So= 2 × 10⁶cm/s. Using this I-V modeling technique to quantitatively determine, So, improvements reduced Soto cm/s. Detector bias has a strong effect on 1/f noise, with minimum 1/f noise occuring at zero bias. Correlation of this 1/f noise in 3-5 µm (Hg,Cd)Te photodiodes with surface G-R was recently reported. Present 8-12µm (Hg,Cd)Te photodiodes are shown to have a similar correlation over the Sorange observed.