Role of Defects in the Transport Properties and Photoresponse of a Silicon–MoS₂ Mixed-Dimensional Van der Waals Heterostructure

Abstract

Heterostructures based on two-dimensional (2D) materials have demonstrated huge potential in various modern-day electronic and optoelectronic devices, but their optoelectronic properties are strongly influenced by the defects present in these materials. Hence, an in-depth understanding of the role of defects is vital in designing high-performance optoelectronic devices. Here, we investigated the role of defects in the electronic transport and photoresponse properties of a silicon−MoS 2 p−n junction heterostructure through temperature-dependent electrical studies and demonstrated a method for improving their photoresponse. The presence of space-charge-limited transport with exponentially distributed trap states was evident from the temperature-dependent I−V characteristics. The temperature dependence of the ideality factor and intensity-dependent photoresponse also elucidated the nature of defects. The amplitude of low-frequency 1/f noise was observed to decrease with an increase in temperature, revealing the significant influence of defects on the charge transport. These defects can often cause recombinations, diminishing the photoresponse and severely degrading the optoelectronic properties. A significant enhancement in photoresponse by reducing the recombination centers was obtained by altering the surrounding dielectric environment. For a particular dielectric, the enhancement was observed to be more prominent toward low temperatures. In addition, the surrounding dielectric also effectively suppressed the low-frequency noise levels in the heterostructure. Insights from this study would help in designing and improving the properties of low-dimensional optoelectronic devices.

Investigating the Electrical Transport and Photoresponse Properties of WSe2 and a Thermally Engineered SrTiO3-Based Heterojunction

“…The standard TE model is I = I 0 .25em exp true( nobreak0em.25em⁡ q V n k T true) [ 1 − exp true( − q V n k T true) ] where I 0 is the reverse saturation current described by the relationship I 0 = A A * T 2 .25em exp ( − q φ b k T ) where A is the effective diode area, A * is the effective Richardson constant, k is the Boltzmann constant, T is the absolute temperature, and φ b is the barrier height of the heterostructure. , Here, the value of the Richardson constant is taken to be 156 A cm –2 K –2 for STO. , The value of the ideality factor is found using the slope of the logarithmic plot of ln I vs V . n = q k T ( d V d ln I ) …”

“…The standard TE model is where I 0 is the reverse saturation current described by the relationship where A is the effective diode area, A * is the effective Richardson constant, k is the Boltzmann constant, T is the absolute temperature, and φ b is the barrier height of the heterostructure. , Here, the value of the Richardson constant is taken to be 156 A cm –2 K –2 for STO. , The value of the ideality factor is found using the slope of the logarithmic plot of ln I vs V . …”

Semiconductor–Semimetal 2D/3D MoS2/SrRuO3(111) TMD/TMO Heterojunction-Based ReRAM Devices

“…The concept of an “Interface as a novel device platform” has been gaining momentum for quite some time since the discovery of many novel phenomena in epitaxial oxide–oxide interface systems. , Lately, the heterostructures of two-dimensional (2D) materials forming three-dimensional (3D) structures have been attracting renewed attention because of the possible new set of intriguing and novel phenomena they can support due to the differing character of the electronic structures. − Indeed, such interfaces alter and induce spin degrees of freedom, charge concentration gradients, and local lattice structure changes, leading to technologically interesting physical phenomena of interest to advanced electronic devices. The 2D/3D interface is another area of great importance as it provides an unprecedented range of interesting new phenomena that are absent in their 3D/3D or 2D/2D counterparts, and are considered an essential foundation for modern electronics. − …”