At present technology of growing of herteroepitaxial structures with variable composition based on CdxHg1-xTe solid solution by the molecular-beam epitaxy method is significantly developed. Now similar semiconductor structures are applied often in the photodetectors of middle and far infrared ranges of spectra.

The subject of this scientific work is the research of energy-band diagrams and capacity-voltage characteristics of CdxHg1-xTe-based variband heteroepitaxial structures with taking into account the dependence of electron affinity on the composition.

In this work numerical simulations of energy-band diagrams and capacity-voltage characteristics for metal-insulator-semiconductor structures based on CdxHg1-xTe-variable composition layers with wide quantum wells (~200 nm) inside the variband layer are carried out. Energy diagrams are calculated with taking into account the dependence of electron affinity on the composition x of CdxHg1-xTe [1, 2]:

χ(x)=5.56-1.23*+0.79*x2-0.83*x3

This dependence was obtained in terms of dependence of local electroneutrality level on the composition for CdxHg1-xTe (see [1]).

It is shown in this work that the taking into account of the dependence of electron affinity on the composition for CdxHg1-xTe in some cases strongly influence on the view of energy structure and capacity-voltage characteristics of variband layers. So, the most influence is observed in depletion and inversion modes of operating of metal-insulator-semiconductor structure.

Also, comparison of calculated and experimental capacity-voltage characteristics is carried out.

References

Gorn D.I., Nesmelov S.N., Voitsekhovskii A.V., Kokhanenko A.P. Calculation of energy-band diagrams of HgCdTe-based variband structures with taking into account the dependence of electron affinity on the composition // Izv. vuzov: Fizika. – 2008. – 9/3. – P. 134–137.

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1. Calculation of radiation defect profiles in CMT subjected to high power laser beams
2. Capacitance-voltage characteristics of MIS-structures in base on graded-band MBE Hg_1-xCd_xTe at passivation epitaxial grown in situ CdTe
3. The influence of near-surface graded-band layers on electrical properties of MIS-structures in base on MBE HgCdTe