Dynamic modes in kelvin probe force microscopy: Band excitation and G-Mode

Since its invention in 1991, Kelvin Probe Force Microscopy (KPFM) has developed into the primary tool used to characterize electrical phenomena on the nanometer scale, with multiple applications for transport, ferroelectric, biological, organic and inorganic photovoltaics, amongst a myriad of other materials. At the same time, this multitude of applications is underpinned by a relatively simple detection scheme utilizing the classical lock-in signal detection combined with tip bias feedback. It has been widely recognized that this detection scheme has several limitations, including influences of the experimental parameters (e.g. driving amplitude, feedback gains, phase offset) as well as loss of information on other material properties (e.g. capacitance and its bias dependence and time-dependent responses). In this chapter, we review the operational principles of KPFM, briefly overview the existing excitation schemes beyond the classical lock-in—feedback principle, and discuss at length the implementations and applications of KPFM based on band excitation and the full information capture embodied in general mode (G-Mode). The future potential pathways for development of detection in KPFM are discussed.