Growth and characterization of InAlP/InGaAs double barrier RTDs
The material system InAlP/InGaAs is of interest especially due to the high conduction band discontinuity at the heterojunction. The composition of In(0.67)AI(0.33)P results in a bandgap of E-G,E-INAIP = 2.01 eV. In this work we present a double barrier In(0.67)AI(0.33)P/In0.55Ga0.45As/In0.67Al0.33P resonant tunnelling diode. The device function is very sensitive to interface effects like roughness, abruptness and homogeneity. The growth of this material system is challenging because of the large lattice mismatch of the Al containing material on an InP substrate. A fully non-gaseous source LPMOVPE configuration is used for the growth. The resonant tunnelling diode structures are characterized by HRXRD measurements, which are compared to simulation result, and dc measurement. A high peak current density of S-p = 3 x 10(5) A/cm(2) at V-Peak = 1.3 V with a peak-to-valley current ratio PVR = 1.2 has been achieved. Both, the symmetric behaviour of the dc-measurement and the X-ray results confirm a high quality of the highly strained InAIP barrier layers and abrupt interfaces to InGaAs.
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