Characterisation of dark current in novel Hg1-xCdxTe mid-wavelength infrared photovoltaic detectors based on n-on-p junctions formed by plasma-induced type conversion
Mh. Rais et al., Characterisation of dark current in novel Hg1-xCdxTe mid-wavelength infrared photovoltaic detectors based on n-on-p junctions formed by plasma-induced type conversion, J CRYST GR, 214, 2000, pp. 1106-1110
This paper reports initial characterisation results for planar mid-waveleng
th infrared (MWIR) photodiodes fabricated using a novel reactive ion plasma
-induced n-on-p junction formation technology on vacancy-doped p-type HgCdT
e grown by LPE on CdZnTe substrates. The junction is formed without the nee
d for post-implant annealing typically required by ion implantation junctio
n formation techniques to repair damage or to move the junction away from d
amaged regions. The dark current and dynamic resistance, R-d, of the fabric
ated photodiodes have been characterised as a function of temperature. At 8
0 K, the zero-bias dynamic resistance-junction area product (R(o)A) of the
diodes is 4.6 x 10(7) Ohm cm(2), with the devices being diffusion limited d
own to similar to 135 K. Dynamic resistance has been measured for temperatu
res between 80 and 195 K and biases between - 200 and + 150 mV. Modelling o
f the observed dark current has been undertaken using three distinct mechan
isms, diffusion, generation-recombination, and tray-assisted tunnelling. Th
e results show that the plasma-induced junction formation technique can pro
duce high-performance planar HgCdTe photodiodes. The dark current mechanism
s found in these devices are similar to those found in diodes formed using
conventional ion implantation techniques. (C) 2000 Elsevier Science B.V. Al
l rights reserved.