Low frequency noise-dark current correlations in HgCdTe infrared photodetectors Article Swipe

In this paper, low frequency noise and dark current correlation is investigated as a function of reverse bias and temperature for short-wave infrared (SWIR), mid-wave infrared (MWIR), and long-wave infrared (LWIR) HgCdTe homo-junction photodetectors. Modelling of dark current-voltage characteristics shows that the detectors have ohmic-behavior under small reverse bias, thus enabling further analysis of 1/ f noise-current dependences with the empirical square-law relation ( S I ∼ I 2 ) at different temperature regions. It is found that for the SWIR and MWIR devices, the total 1/ f noise spectral density at arbitrary temperatures can be modelled by the sum of shunt and generation-recombination noise as <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi>S</mml:mi> <mml:mi>I</mml:mi> </mml:msub> </mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>T</mml:mi> <mml:mo>,</mml:mo> <mml:mspace width="thickmathspace"/> <mml:mi>f</mml:mi> </mml:mrow> <mml:mo stretchy="false">)</mml:mo> <mml:mo>=</mml:mo> <mml:mo stretchy="false">[</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi>α</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>S</mml:mi> <mml:mi>H</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> <mml:msubsup> <mml:mi>I</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>S</mml:mi> <mml:mi>H</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msubsup> <mml:mo stretchy="false">(</mml:mo> <mml:mi>T</mml:mi> <mml:mo stretchy="false">)</mml:mo> <mml:mo>+</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi>α</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>G</mml:mi> <mml:mo>−</mml:mo> <mml:mi>R</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> <mml:msubsup> <mml:mi>I</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>G</mml:mi> <mml:mo>−</mml:mo> <mml:mi>R</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msubsup> <mml:mo stretchy="false">(</mml:mo> <mml:mi>T</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mo stretchy="false">]</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mi>f</mml:mi> </mml:math> , with no contribution from the diffusion component observed. On the other hand, for the LWIR device the diffusion component induced 1/ f noise that cannot be overlooked in high temperature regions, and a 1/ f noise-current correlation of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi>S</mml:mi> <mml:mi>I</mml:mi> </mml:msub> </mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>T</mml:mi> <mml:mo>,</mml:mo> <mml:mspace width="thickmathspace"/> <mml:mi>f</mml:mi> </mml:mrow> <mml:mo stretchy="false">)</mml:mo> <mml:mo>=</mml:mo> <mml:mo fence="false" stretchy="false">{</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi>α</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:mrow> <mml:mo stretchy="false">[</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msubsup> <mml:mi>I</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>D</mml:mi> <mml:mi>I</mml:mi> <mml:mi>F</mml:mi> <mml:mi>F</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msubsup> <mml:mo stretchy="false">(</mml:mo> <mml:mi>T</mml:mi> <mml:mo stretchy="false">)</mml:mo> <mml:mo>+</mml:mo> <mml:msubsup> <mml:mi>I</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>G</mml:mi> <mml:mo>−</mml:mo> <mml:mi>R</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msubsup> <mml:mo stretchy="false">(</mml:mo> <mml:mi>T</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mo stretchy="false">]</mml:mo> <mml:mo>+</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi>α</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>S</mml:mi> <mml:mi>H</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> <mml:msubsup> <mml:mi>I</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi>S</mml:mi> <mml:mi>H</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msubsup> <mml:mo stretchy="false">(</mml:mo> <mml:mi>T</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mo fence="false" stretchy="false">}</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mi>f</mml:mi> </mml:math> is proposed, with a shared noise coefficient of α s ≅ 1 × 10 −9 which is close to that calculated for shunt noise. The 1/ f noise-current correlation established in this work can provide a powerful tool to study the low frequency noise characteristics in HgCdTe-based photodetectors and to help optimizing the “ true ” detectivity of devices operating at low frequency regime.