Aging degradation of a Gunn diode due to induced dislocations

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Abstract
The influence of thermocompression bonding condition on the gradual degradation of a Gunn diode, accompanied by an increase of the low-field resistance, was studied. It was found that the diodes bonded with a higher pressure or at a higher temperature degrade in a shorter aging period. Many dislocations are easily induced into the GaAs chip by thermocompression bonding. Dislocations are also induced into the GaAs chip during aging, if mechanical strain remains in the GaAs chip after the bonding. The presence of many dislocations accelerates copper diffusion in GaAs and increases the acceptor concentration due to diffused copper in the epitaxial GaAs layer. It was concluded from these results that gradual degradation of the Gunn diode in question originates from the dislocations induced at the thermocompression bonding or during the aging, although it has not been clear yet whether the contamination by copper through the dislocations or the multiplication of dislocations during the aging is the dominant process.