Surface leakage current analysis of ion implanted ZnS-passivated n-on-p HgCdTe diodes in weak inversion

Abstract

Effects of fixed charge on R 0 A value of ZnS-passivated x = 0.3 HgCdTe n-on-p diode are explained as a shunt resistance that affects current-voltage (I-V) and dynamic resistance-voltage (Rd-V) characteristics. The fixed charge of 1 × 10 11 /cm 2 to 2 × 10 11 /cm 2 which is usually obtained with ZnS passivation makes the surface weakly inverted and reduces HgCdTe diode R 0 A value owing to the short generation lifetime of HgCdTe substrate. The gate-controlled diode and specially fabricated diode are used to explain the surface leakage current in the weak inversion and charge sheet model is used to explain the characteristics. It is found that the surface leakage current by the inverted channel in the weak inversion can reduce R 0 A more than other currents such as the generation current and tunneling current which are usually used to explain the surface leakage current of HgCdTe diode.

Accurate Simulation of Temperature-Dependent Dark Current in HgCdTe Infrared Detectors Assisted by Analytical Modeling

“…Inset shows reported experimental data for a mid-wave gated n-on-p HgCdTe diode. 24 charge of 1 9 10 11 cm À2 at the surface passivation layer can be expected in the numerical simulations. Our work presents an efficient approach for darkcurrent modeling over wide temperature and bias voltage ranges, which is important for investigating the mechanisms of carrier transport across the HgCdTe junction.…”

“…For ZnS-passivated n + -on-p LW MCT photodiodes, a fixed charge of 1 9 10 11 cm À2 to 2 9 10 11 cm À2 can be found at the device surface. 24 To take into account the effects of surface passivation on device performance, fixed interface charge of 1 9 10 11 cm À2 was included at the ZnS-passivation/ HgCdTe interface in our numerical simulations. The leakage current induced by the fixed charge was assumed not to change with applied voltage for the selected temperatures.…”

Temperature dependence of ohmic shunt resistance in mercury cadmium telluride junction diode

“…Such a large variation in the value of D it is unlikely to occur from diodeto-diode spaced within a distance of 1.3 mm within an array. Also, the reported [16][17][18][19][20][21] range of D it in HgCdTe-ZnS interface is 1 · 10 11 -6 · 10 12 cm À2 . Alternatively, this observation points out towards the possibility of high dislocation density material beneath the diode #103/43 as concluded previously [5].…”

“…In ZnS passivated HgCdTe samples, both positive and negative interface fixed charges have been reported [16][17][18][19][20]. This means that one could obtain either accumulation or depletion of the surface of p-type material around n þ region depending upon the sign of fixed charges.…”

“…Broken line curves exhibit calculated temperature dependence of shunt resistance for two positive (accumulation) values of Q SC . Further to cover a wide range of values of D it (1 · 10 11 -6 · 10 12 cm À2 ) reported in the literature [16][17][18][19][20][21], calculations have been carried out for a low D it value of 1 · 10 11 cm À2 and a high value of 1 · 10 12 cm À2 . It is seen that the experimental data is nowhere near to the theoretical curves for fixed negative interface charges.…”