The concept utilized in charge coupled devices (CCD’s) for detection and imaging of light signals involving lateral movement of charges and extremely low capacitance of the detector and readout electronics has spawned a variety of new ideas in the design of nuclear detectors. Initially, silicon drift detectors (SDD’s) were developed for high energy physics applications. More recently, a vigorous effort to develop new structures for x-ray spectroscopy and light detection has started. Drift structures have been designed in a variety of topologies and materials (such as Si, CdZnTe, and HgI2) to satisfy the requirements of many different applications. The most interesting features that can be achieved with drift structures include: a) Large active area devices with low capacitance and low electronic noise, b) Very high signal throughput, c) Operation at or near room temperature, d) High sensitivity over the large entrance electrode to low energy xrays and short wavelength light, f) Single carrier charge collection allowing for elimination of hole contribution to the spectral broadening in compound semiconductor detectors such as HgI2, CdTe, and CdZnTe, f) 2D resolution of few tens of micrometer in both directions over few cm2 active areas, and g) Possibility of using more sophisticated schemes of charge collection by switching between integration and drift mode.