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 epitaxi al (MOVPE) reactor with a rotating susceptor. AlAs had a much narrower plateau of saturated growth as compared to GaAs and Al0.3Ga0.7As, whi ch would be due to the higher Al-CH3 bond energy. ALE was used to achi eve p+-AlGaAs in the 10(20) cm-3 range using carbon originated from th e organometallic sources. ALE grown p+-Al0.3Ga0.7As/n+-GaAs heterojunc tion tunnel diodes showed high peak current density of 40 A/cm2 and hi gh peak-to-valley ratio of 10, which were obtained from a half of 2-in ch diameter wafer. The diodes were successfully applied to interconnec t the high and low bandgap cells in AlGaAs/GaAs tandem solar cells wit hout any degradation of electrical performance.