  We present methods to improve the energy resolution of single-channel,
room-temperature Cadmium-Zinc-Telluride (CZT) detectors. A new preamplifier
design enables the acquisition of the actual transient current from the
crystals and straightforward data analysis methods yield unprecedented energy
resolution for our test-detectors. These consist of an eV-CAPture Plus crystal
as standard and 1 cm cube Frisch collar crystals created in-house from
low-grade coplanar grid detectors. Energy resolutions of 1.9% for our collar
detectors and 0.8% for the eV crystal at 662 keV were obtained. The latter
compares favourably to the best existing energy resolution results from pixel
detectors.
