Rapid zinc diffusion behaviors in lightly doped extended wavelength In0.83Ga0.17As focal plane arrays

Abstract

Zinc diffusion behaviors in n type In0.83Ga0.17As epitaxial layers doped to 3.5 × 1015 cm−3 are investigated for the planar type extended wavelength In0.83Al0.17As/In0.83Ga0.17As focal plane arrays by incorporating the vacancy-related complex defect (VCD) model. The diffusion coefficients extracted from the measured zinc concentration profiles at 480 °C are determined to be 3.1 × 10−12 and 4.3 × 10−11 cm2/s for the kick-out and the VCD models, respectively. Both mechanisms compete with each other during the dynamic zinc atom drive-in process. The diffusion activation energies for two mechanisms are 0.56 and 0.06 eV, indicating that the VCD model is not quite sensitive to the temperature compared with the kick-out model. The higher diffusion coefficient of the VCD model renders the occurrence of an anomalous rapid drive-in process with a lower concentration in the lightly doped epitaxial layer, leading to the increased dark current densities of 0.052 A/cm2 at 300 K and 8.85 × 10−7 A/cm2 at 140 K with −10 mV bias. By precise control of the diffusion depth, low dark current densities at −10 mV were obtained with 1.84 × 10−3 A/cm2 at 300 K and 4.5 × 10−9 A/cm2 at 140 K. The high peak specific detectivity (D*) up to 1.89 × 1013 cm Hz1/2 W−1 is achieved under a long integration time of 400 ms with the pixel operability of 99.4%.