Highly sensitive Al0.25Ga0.75As/In0.25Ga0.75As/GaAs quantum-well Hall devices with Si-delta-doped GaAs layer grown by LP-MOCVD

Abstract

Quantum-well Hall devices based on Si-delta-doped Al0.25Ga0.2As/In0.25Ga0.75As/GaAs pseudomorphic heterostructure materials grown by the low-pressure metal organic chemical vapour deposition (LP-MOCVD) method have been successfully fabricated. A Si-delta-doped GaAs layer is introduced for the first time in the Hall device to reduce the thermal variation of electron concentrations and to improve its temperature characteristics. A high electron mobility of 8100 cm(2) V-1 s(-1) with a sheet carrier density of 1.5 X 10(12) cm(-2) has been achieved at room temperature. A temperature coefficient of - 0.015% K-1 with a product sensitivity of 420 V A(-1) T-1 has been obtained. High signal-to-noise (S/N) ratios corresponding to minimum detectable magnetic fields (B-min) of 60 nT at 1 kHz and 110 nT at 100 Hz have been attained due to the reduced low-frequency noise from DX centres and the high mobility, These data belong to one of the best reported results.