GaInP/GaInAs/GaAs structures for high performance MODFETs. Design, growth procedure, Hall data and device properties

A new type of GaInP/GaInAs/GaAs layer structure for MODFET devices has been developed. The novel feature of this structure is a compositionally modulated, pseudomorphic GaInP barrier which is suited to achieve record breaking two dimensional electron densities in GaInP/GaInAs/GaAs structures. Densities upwards of 3/spl times/10/sup 12//cm/sup 2/ with single-sided doping, and over 5/spl times/10/sup 12//cm/sup 2/ with double-sided doping have been obtained. Furthermore, it is demonstrated that buffer layers as thin as 2.5 nm are sufficient to achieve electron mobilities of more than 6000 cm/sup 2//Vs (RT) for electron densities of 3/spl times/10/sup 12//cm/sup 2/ in MODFET structures grown on top of these thin buffer layers. MODFET devices fabricated on this type of heterostructure using only 10 nm thick buffers have output transconductances and pinch off characteristics competing favourably with AlGaAs/GaInAs/GaAs MODFET devices fabricated on MBE grown structures. Intrinsic transconductances of 700 mS/mm and ft and fmax values of 100 and 180 GHz, respectively, demonstrate the potential of the new Al free structures.