Fabrication of in-plane-gate transistor structures by focused laser beam-induced Zn doping of modulation-doped GaAs/AlGaAs quantum wells

Local Zn doping of n-modulation-doped GaAs/AlGaAs quantum well samples induced by absorption of a focused laser beam has been used to fabricate in-plane-gate transistor structures. Laser-induced thermal Zn diffusion from a highly doped SiO2 emulsion into the sample surface layers allows direct writing of lateral npn structures with sub-μm resolution. The p-doped lines form lateral potential barriers which are efficiently isolating the gate electrodes for large applied voltages at room temperature. Transistor structures with a 3-μm-wide electron channel in between V-shaped gates yield a transconductance of about 50 μS and are pinched-off at gate voltages UG≤−2.0 V.