Bulk unipolar diodes formed in GaAs by ion implantation

In an attempt to emulate epitaxially manufactured semiconductor multilayers for microwave device applications, we have produced a camel diode structure in GaAs for the first time, using the tail of a Mg ⁺ implant into a molecular beam epitaxially grown n ⁺-n ^--n ⁺ structure. Using a range of ion energies and doses, samples are observed to exhibit bulk unipolar diode characteristics. With low dose and energy, a diode with barrier height of ∼0.8 V and ideality factor ∼1.25 is achieved. 'Punch through' diode characteristics are obtained at high ion dose and energy, some with knee voltages in excess of 7 V.