Charge-Carrier Mobilities in II-VI-Based Organic-Inorganic Hybrid Superlattice Nanostructures*

β-ZnTe(en)_0.5 is a member of II-VI-based organic-inorganic hybrid nanostructures, features a uniform and fully ordered short-period superlattice structure without physical or chemical fluctuations. The thickness of the inorganic sheets, consisting of two monolayers of ZnTe, is comparable to that of 2D materials. In this structure, zinc atoms from two monolayers of ZnTe alternate with nitrogen atoms from an organic component (ethylenediamine) along the stacking axis (b-axis), creating periodically stacked quasi-2D superlattice nanostructures. The unique heterostructure of β-ZnTe(en)_0.5 characterized by its thickness, stackability, and quantum confinement properties, resembles emerging 2D superlattice heterogeneous structures, making it advantageous for integration into (opto)electronic devices. Additionally, the exceptional long-term stability further enhances its potential for (opto)electronic applications.

The Space-Charge-Limited Current (SCLC) measurement is a convenient, simple, yet powerful two-probe electrical technique used to investigate space-charge transport properties, trap density, and energy distribution of carrier trapping states in semiconductors. However, SCLC measurement analysis may be prone to misinterpretation, as the method was originally developed for the conduction mechanism of ions in a vacuum diode. The Mott-Gurney (MG) law is proposed as a more suitable framework for interpreting SCLC behavior in ideal devices, especially for studying charge-carrier mobility through drift currents.

Partial degradation is observed in β-ZnTe(en)_0.5 after exposure to chemicals used in the photolithography process, and stencil lithography approach is used to minimize chemical exposures.

The MG-law has been employed in SCLC measurements to determine the carrier mobility of β-ZnTe(en)_0.5 along three symmetry axes. Along the organic-inorganic stacking direction (b-axis), the mobilities are on the order of 10^-3 cm²/(Vs). In contrast, the mobility in the plane parallel to the inorganic sheets (a- and c-axis) is anisotropic, ranging from 10 to 100 cm²/(Vs).