Wafer bonding is an established technology for the manufacturing of silicon-on-insulator (SOI) substrates, microelectromechanical systems (MEMS) and microfluidic devices. Low temperature direct bonding techniques can be of particular interest for the fabrication of monolithic radiation sensors. Such techniques allow the joining of various absorbers on the backside of thinned CMOS circuity without intermediate layers or through vias. This paper presents a method for the electrical characterization of such bonded interfaces based on the Transient Current Technique (TCT). This method can be extended to the investigation of any type of solid-state devices. (c) 2019 Author(s).