The detailed theory of two terminal triangular barrier devices including minority carrier effects is investigated. Most of the available theories describing the operation of the traingular barrier diode are analysed and compared with each other. Novel experimental d.c. results for triangular barrier diodes are presented for structures with different asymmetries and zero bias barrier heights. Six different designs for triangular barrier switches are all shown to display switching action. The switching threshold is shown to be a sensitive function of the area doping concentration of the p-plane and of the asymmetry of the zero-bias potential barrier. The measured switching thresholds are in broad agreement with theoretical predictions from the minority models discussed and a substantial database is provided for future work. The triangular barrier switch is optically sensitive and may be switched by a pure electrical signal, pure optical signal, or some combination of the two. The triangular barrier switch is shown to be a fast regenerative switching element with a 10-90% turn-on time of < 300 ps. The nature of the dominant electron current conduction mechanism in a triangular barrier switch is shown to vary with temperature. The three regions of operation for the traingular barrier switch at different temperatures i.e. field emission, thermionic-field emission and thermionic emission, are defined for a given structure and verified experimentally. There is good agreement between theoretical and experimental results. The applications of the triangular barrier diode and the triangular barrier switch are discussed. One application of the triangular barrier switch is demonstrated experimentally: it is used as a variable width pulse generator with well defined rise and fall times determined by the turn-on response of the triangular barrier switch.