ZnO/SiO2/Si surface acoustic wave Love mode sensors are considered to be promising high sensitivity sensors. Previous research has tested ZnO/SiO2/Si SAW sensors with selected operating frequency and guiding layer thickness. This investigation is based on experimental data of previous research and used the theories and equations from that research to evaluate and develop a model of the mass sensitivity of surface acoustic wave (SAW) devices with two different piezoelectric semiconductors, ZnO/SiO2/Si and GaN/SiO2/Si Love mode SAW sensors. The SAW mass sensitivity model developed here, examined the mass sensitivity of the SAW device with respect to the design parameters, like wavelength, piezoelectric layer thickness, and the two different semiconductors (ZnO, and GaN) to obtain optimum mass sensitivity. The mass sensitivity increases when the wavelength is increasing. The model also shows that the maximum mass sensitivity of GaN-based devices is 10% better than the maximum mass sensitivity of ZnO-based devices.