ABSTRACT
ABSTRACT
This work investigates the mechanical properties of semiconductors at both bulk and nanoscale levels, emphasizing the relationships among bond strength, elastic moduli (Young’s modulus and Bulk modulus), mean bond length, bond ionicity, and bond energy. A comprehensive theoretical framework is established to examine the size-dependent characteristics of nanocrystalline semiconductors, encompassing nanofilms (NFs), nanowires (NWs), and nanoparticles (NPs). A definitive correlation exists between the mean bond length (
) and bond energy (
) for bulk tetrahedral semiconductors (group IV, III-V, II-VI, I-III-VI₂, II-IV-V₂, I₂-IV-VI₃, I₃-V-VI₄, and III₂-VI₃): 
, where 
denotes bond ionicity (ranging from 0 to 0.75). This relation is utilized to calculate previously inaccessible for different semiconductor categories. At the nanoscale, size-dependent phenomena are integrated via altered and . For nanocrystals of tetrahedral semiconductors, the bulk modulus 
is as follows: 
.
The bond strength (
) is defined by the equation: 
. The findings indicate that mechanical properties alter as size and dimensionality decrease, especially for NPs smaller than 2 nm. The 
of Si diminishes from 98 GPa (bulk) to 76 GPa (2 nm NPs), the relationship newly established in this work demonstrates that Young’s modulus, 
, decreases as a consequence of the increased surface-to-volume ratio, which in turn results in a rise in for both semiconductors and metals. NPs exhibit the most significant decline, compared to NWs and NFs, with NWs falling in the intermediate range. These trends are ascribed to nanoscale changes in and . Theoretical calculations correspond closely with experimental and computational evidence, affirming the model’s validity. This work presents a cohesive model for comprehending size-dependent mechanical characteristics in semiconductors, delivering insights for the design and enhancement of nanostructured materials and devices. The results underscore the essential influence of bond attributes and surface phenomena in modulating the mechanical properties of nanocrystals.
