Electrical, photoconductive, and photovoltaic characteristics of a Bi2Se3 3D topological insulator based metal-insulator-semiconductor diode.

A metal-insulator-semiconductor (MIS) diode based on the Bi 2 Se 3 3D topological insulator on p-Si substrate was fabricated for use as a photodiode with the Al/p-Si/Bi 2 Se 3 /Al structure. The current-voltage, series resistance, and impedance characteristics were investigated using standard techniques and a new series resistance compensated method. The application of the method is described in a brief algorithm. The diode exhibits an apparent rectification ratio of 3700 and the R s compensated rectification ratio that is almost 1.5 times higher, thus suggesting a new method to determine the true rectification ratio of a diode. The diodes have an ideality factor greater than unity, a barrier height of 0.647 eV, and a built-in potential of 0.476 V. The maximum density of the interface state of the diode is 5.1 × 1012 eV−1cm−2 over the reverse bias range of − 3–0 V. This is comparable to those of oxide-based diodes, but unexpected since oxygen-induced defect states were thought unlikely. When compensating for the effects of series resistance, the dark current of the diode is found to be 2.5 nA. The open-circuit voltage of the diode was estimated at around 0.244 V at 100 mW/cm2 solar light illumination, with an estimated efficiency of at most 2.9%. These values are typically reported bismuth-based topological insulator/Si diodes. This shows that the diode can be used as a low-power solar cell. The photoresponses of the device show that it is suitable as a fast MIS photodiode over a wide range of incident intensity. [Display omitted] • Bi2Se3 3D-topological insulator based diode for photoconductive sensing. • High open-circuit voltage of 0.244 V and short-circuit current up to 57.8 uA for photovoltaics. • Application of powerful new series resistance compensation technique for analysis. • New method suggested for true rectification ratio of diodes with series resistance. • Devices demonstrate efficiencies of up to 2.9. [ABSTRACT FROM AUTHOR]