THE ELECTRICAL BREAKDOWN PROPERTIES OF GAAS-LAYERS GROWN BY MOLECULAR-BEAM EPITAXY AT LOW-TEMPERATURE

The electrical properties of as-grown low temperature (LT) GaAs grown at 200-300 degrees C have been investigated in the temperature range o f 100-400 K. It was found that the resistivity of the LT GaAs layer in creased as the growth temperature was increased from 200 degrees C to 300 degrees C. Correspondingly, over the same growth temperature range , the breakdown field decreased from 320 kV cm(-1) to 80 kV cm(-1), ye t was more than one order of magnitude higher than that semi-insulatin g GaAs. The breakdown voltage V-BD was found to increase as the measur ement temperature was decreased, differing from the behaviour of conve ntional avalanche breakdown. The transport properties of LT GaAs were characterized by hopping conduction at low electric field and low temp erature. The particular properties of the as-grown LT GaAs layers sugg est a useful application as an insulator in GaAs field effect transist ors (FETS). The predominant ohmic behaviour, resulting from hopping co nduction, produces a uniform field in the material, which prevents the breakdown at the gate edge of the FETs or at the surface. The high br eakdown strength suggests enhanced performance in power devices.