(111)B-oriented AlAs/GaAs/AlAs double barrier resonant tunneling devices grown in a gas source molecular beam epitaxy system

We have studied the growth of(lll)B-oriented AlAs/GaAs/AlAs double barrier resonant tunneling structures in a gas source molecular beam epitaxy system. We investigate the current peak-to-valley ratios of the resonant tunneling structures grown on (111)B GaAs substrates under the various growth conditions, such as III/V flux ratios, substrate temperature, growth interruption at the heterointerfaces, buffer or contact layers, etc. We demonstrate that, in contrast to previous reports, high quality heterostructures can be grown in a gas source system if certain III/V flux ratio, substrate temperature, and misoriented substrate are used. We show that the As/Ga flux ratio plays the key role for the growth on the misoriented (111)B GaAs substrate, and growth at extremely high temperatures is not beneficial to the negative differential resistance. We also show that, although inserting a growth interruption in the buffer layer is believed to be helpful to the surface morphology, it is detrimental to the current peak-to-valley ratio.