First observation of ballistic holes in a p-type THETA device

Novel p-type tunneling hot electron transfer amplifier (THETA) devices have been fabricated for the first time. A tunnel injector is used to separate the light holes from the heavy ones. In the present case, in p GaAs doped to 2×10¹⁸ cm^-3, the fraction of light holes is only about 6%. After tunneling through a 10-nm-thick AlGaAs barrier, 0.2-eV high, the current due to light holes is more than 10⁴ times greater than that due to the heavy holes. This method of injection has been used to launch primarily light holes into a 30-nm p-GaAs layer, doped as above, and performed energy spectroscopy with another, relatively thick, AlGaAs spectrometer barrier at the exit. It was found that 10% of the injected holes traversed the GaAs layer and the spectrometer ballistically with narrow energy distributions, 35-meV wide. The nature of the ballistic transport was also independently verified to be due to the light holes. This was done through the observation of quantum interference effects of the ballistic holes in the thin GaAs base. The results show that p-type ballistic devices with performance potential approaching that of n-type devices may be possible