Local two-dimensional electron gas formation in p-doped GaAs/InyGa1-yAs/AlGa1-xAs heterostructures by focused Si-implantation doping

To investigate the possibility of fabricating two-dimensional bipolar devices by focused ion implantation doping, selectively p-doped GaAs/InyGa1-yAs/AlxGa1-xAs heterostructures containing a two-dimensional hole gas (2DHG) were implanted with Si to overcompensate the p-doping locally and create a laterally structured two-dimensional electron gas (2DEG). In this way, a two-dimensional p-n junction can be formed. The p-doped base material had a hole concentration of p = 5.4 x 10(11) cm(-2) and a hole mobility of 240 cm(2) V-1 S-1. Si was implanted with 60 keV at doses from 2 x 10(12) cm(-2) to 2 x 10(11) cm(-2), using a focused ion beam system. Up to implantation doses of 1 x 10(13) cm(-2), the formation of a 2DEG without unwanted parallel conducting channel was observed. For higher implanted doses additional three-dimensional conduction is observed. The highest electron concentration obtained without parallel conduction was 5 x 10(11) cm(-2) at 300 K as well as at 4.2 K. The corresponding mobilities are 5000 cm(2) V-1 s(-1) at room temperature and 6000 cm(2) V-1 s(-1) at 4.2 K. A first two-dimensional p-n junction fabricated by this method showed good I-V characteristic of a diode.