Atomic layer epitaxy of device quality AlGaAs and AlAs

Atomic layer epitaxy (ALE) of device quality AlGaAs and AlAs has been demonstrated on a modified commercial metalorganic vapor phase epitaxial (MOVPE) reactor with a rotating susceptor. AlAs had a much narrower plateau of saturated growth as compared to GaAs and Al0.3Ga0.7As, which would be due to the higher Al-CH3 bond energy. ALE was used to achieve p+-AlGaAs in the 1020 cm-3 range using carbon originated from the organometallic sources. ALE grown p+-Al0.3Ga0.7As/n+-GaAs heterojunction tunnel diodes showed high peak current density of 40 A/cm2 and high peak-to-valley ratio of 10, which were obtained from a half of 2-inch diameter wafer. The diodes were successfully applied to interconnect the high and low bandgap cells in AlGaAs/GaAs tandem solar cells without any degradation of electrical performance.