Metalorganic vapor phase epitaxy-grown GaP/GaAs/GaP and GaAsP/GaAs/GaAsP n-type resonant tunnelling diodes

We have studied GaP/GaAs/GaP and ${\mathrm{GaAs}}_x{\mathrm{P}}_{\text{1−x}}/{\mathrm{GaAs/GaAs}}_x{\mathrm{P}}_{\text{1−x}}$ double-barrier resonant tunnelling diodes grown by metalorganic vapor phase epitaxy. We find that GaP tensile strained barriers in GaP/GaAs/GaP diodes may be grown with a barrier thickness below the critical thickness of about 12 monolayers. However, a corrugation of the strained barrier is observed by transmission electron microscopy. This variation may explain the low peak-to-valley ratio of the diodes (about 2). In contrast, ${\mathrm{GaAs}}_x{\mathrm{P}}_{\text{1−x}}/{\mathrm{GaAs/GaAs}}_x{\mathrm{P}}_{\text{1−x}}$ resonant tunnelling diodes have been grown with a homogeneous thickness of the barriers, consequently showing a substantially improved electrical performance compared to the GaP diodes with peak-to-valley ratios >5.