Mercury cadmium telluride

HgCdTe or mercury cadmium telluride (also cadmium mercury telluride, MCT, MerCad Telluride, MerCadTel, MerCaT or CMT) is an alloy of cadmium telluride (CdTe) and mercury telluride (HgTe) with a tunable bandgap spanning the shortwave infrared to the very long wave infrared regions. The amount of cadmium (Cd) in the alloy can be chosen so as to tune the optical absorption of the material to the desired infrared wavelength. CdTe is a semiconductor with a bandgap of approximately 1.5 electronvolts (eV) at room temperature. HgTe is a semimetal, which means that its bandgap energy is zero. Mixing these two substances allows one to obtain any bandgap between 0 and 1.5 eV. HgCdTe or mercury cadmium telluride (also cadmium mercury telluride, MCT, MerCad Telluride, MerCadTel, MerCaT or CMT) is an alloy of cadmium telluride (CdTe) and mercury telluride (HgTe) with a tunable bandgap spanning the shortwave infrared to the very long wave infrared regions. The amount of cadmium (Cd) in the alloy can be chosen so as to tune the optical absorption of the material to the desired infrared wavelength. CdTe is a semiconductor with a bandgap of approximately 1.5 electronvolts (eV) at room temperature. HgTe is a semimetal, which means that its bandgap energy is zero. Mixing these two substances allows one to obtain any bandgap between 0 and 1.5 eV. HgCdTe has a zincblende structure with two interpenetrating face-centered cubic lattices offset by (1/4,1/4,1/4)ao in the primitive cell. The cations (Cd or Hg) form the yellow sublattice while the Te anions form the grey sublattice per the adjacent diagram. The electron mobility of HgCdTe with a large Hg content is very high. Among common semiconductors used for infrared detection, only InSb and InAs surpass electron mobility of HgCdTe at room temperature.At 80 K, the electron mobility of Hg0.8Cd0.2Te can be several hundred thousand cm2/(V·s). Electrons also have a long ballistic length at this temperature; their mean free path can be several micrometres. The intrinsic carrier concentration is given by n i ( t , x ) = ( 5.585 − 3.82 x + ( 1.753 ⋅ 10 − 3 ) t − 1.364 ⋅ 10 − 3 t ⋅ x ) ⋅ 10 14 ⋅ E g ( t , x ) 0.75 ⋅ t 1.5 ⋅ e − E g ( t , x ) ⋅ q 2 ⋅ k ⋅ t {displaystyle n_{i}(t,x)=(5.585-3.82x+(1.753cdot 10^{-3})t-1.364cdot 10^{-3}tcdot x)cdot 10^{14}cdot E_{g}(t,x)^{0.75}cdot t^{1.5}cdot e^{frac {-E_{g}(t,x)cdot q}{2cdot kcdot t}}} where k is Boltzmann's constant, q is the elementary electric charge, t is the material temperature, x is the percentage of cadmium concentration, and Eg is the bandgap given by E g ( t , x ) = − 0.302 + 1.93 ⋅ x + ( 5.35 ⋅ 10 − 4 ) ⋅ t ⋅ ( 1 − 2 ⋅ x ) − 0.81 ⋅ x 2 + 0.832 ⋅ x 3 {displaystyle E_{g}(t,x)=-0.302+1.93cdot x+(5.35cdot 10^{-4})cdot tcdot (1-2cdot x)-0.81cdot x^{2}+0.832cdot x^{3}} Using the relationship λ p = 1.24 E g {displaystyle lambda _{p}={frac {1.24}{E_{g}}}} , where λ is in µm and Eg. is in electron volts, one can also obtain the cutoff wavelength as a function of x and t: λ p = ( − 0.244 + 1.556 ⋅ x + ( 4.31 ⋅ 10 − 4 ) ⋅ t ⋅ ( 1 − 2 ⋅ x ) − 0.65 ⋅ x 2 + 0.671 ⋅ x 3 ) − 1 {displaystyle lambda _{p}=(-0.244+1.556cdot x+(4.31cdot 10^{-4})cdot tcdot (1-2cdot x)-0.65cdot x^{2}+0.671cdot x^{3})^{-1}}