InAs/GaSb süperörgü fotodedektörlerde karanlik akim kontrolü

Since every object with a finite temperature accepted to emit infrared radiation, detection of this part of the electromagnetic spectrum is very important. For example the temperature of the exhaust of a vehicle or a missile makes it radiate in the midwave window or the body temperature of a person makes it glow in the long-wave window. Therefore detection in mid-wave and long-wave windows of infrared radiation spectrum is useful for both military and civil purposes. In order to satisfy the need in these field thermal and optical detectors are being developed. Optical detectors are based on the absorption of the thermally generated photons from the objects. However, due to the low energy of the infrared radiation narrow band gap materials are needed to be used. Having narrow gap seems to be useful but the energy required to make an electron to excite from the valance band to conduction band can also be supplied by the ambient temperature. This situation is the main disadvantage of optical detectors. There are too many mechanisms that can generate dark current in the device which make the optically generated current to be less measurable and reduce the device performance. In order to solve this unintentional current problem, optical detectors should be cooled down to cryogenic temperatures. Even for this low temperature regime generation-recombination, tunneling and surface leak currents are not suppressed enough. To increase the device performance these mechanisms should be suppressed. Suppression of surface leakage current which is caused by the dangling bonds on the device side-walls can be achieved with a passivation layer that eliminates the surface states. This thesis suggests the usage of two new methods for passivation of InAs/GaSb type II superlattice mid-waveinfrared detectors. Application of atomic layer deposited Al2O3 and monolayer thick octadecanethiol as passivation layers are compared with their respective unpassivated detectors on their effect on suppression of dark current. Additionally, contact resistance measurements are made in order to check that if there is a contribution from the contact structures that can complicate our device model.Keywords: InAs/GaSb, Infrared photodetector, Passivation, Al2O3, Octadecanethiol