Excess low frequency noise/I-V studies in p-on-n MBE LWIR Hg1-xCdxTe detectors

Excess low frequency noise is investigated for the first time in infrared M BE grown LWIR Hg1-xCdxTe double layer planar heterostructure (DLPH) detecto rs grown on lattice matched substrates. LWIR detectors having R(o)A(opt) va lues at 40K in the 10(1)-10(7) Omega-cm(2) range have been characterized as a function of temperature between 120 and 20K. Detectors with R(o)A(opt) g reater than or equal to 10(3) Omega-cm(2) at 40K have theoretical diffusion limited performance down to 78K and detectors with R(o)A(opt) greater than or equal to 10(5) Omega-cm(2) at 40K are within a factor of two of theoret ical diffusion limited performance for T > 65K. Activation energies extract ed from noise (V-d = -100 mV) and dark current (V-d = -100 mV) vs temperatu re measurements were detector dependent. The activation energy for detector s with R(o)A(opt) approximate to 10(6) Omega-cm(2) at 40K is similar to 0.9 0*E-g to 0.99*E-g. The noise measured between 78 and 105K in the intermedia te performance (R(o)A(opt) similar to 10(3)-10(4) Omega-cm(2) at 40K) detec tors are higher than the noise measured in the higher performance (R(o)A(op t) similar to 10(5)-10(7) Omega-cm(2)) detectors. In addition, the excess l ow frequency noise and the dark current at -100 mV in the intermediate and poor (R(o)A(opt) similar to 10(1) Omega-cm(2)) performance detectors are te mperature independent. For each detector measured, the activation energy ex tracted from noise (V-d = -100 mV) vs temperature measurements is equal to the activation energy extracted from the total dark current (V-d = -100 mV) vs temperature measurements. For different dark current mechanisms, the ex cess low frequency noise varies with temperature and also with area within statistical accuracy in the same manner as the total dark current through t he detector. At 78K, the Tobin(14) expression holds in the general sense fo r equal area detectors dominated by different current mechanisms and also f or detectors with a wide range of implant dimensions (A(imp) = 3.85 x 10(-7 ) cm(2) to A(imp) = 6.25 x 10(-4)cm(2)). Following measurements, the detect ors were stripped of the passivation and overlaying metal layers and dresse d by a defect etch to reveal defects in each detector. A correlation among noise, leakage current and defect type has been determined for each detecto r.