Study of doping concentration variation in InGaAs/InP high electron mobility transistor layer structures by Raman scattering

The effect of varying the dopant concentration (N-D) in the InP donor layer of In0.53Ga0.47As/InP high-electron mobility transistor (HEMT) Structure w as studied by Raman scattering measurements. The carrier concentration in t he InGaAs channel was found to increase when the doping concentration in th e donor layer was increased assuming that the donors are fully ionized. The coupled mode between the InGaAs longitudinal optical phonons and the elect rons in the InGaAs channel shifts continuously to a lower wave number with the increase in the value of N-D in the InP donor layer. The correlation be tween the observed Raman shift with the carrier concentration in the channe l layer can be used to characterize the HEMT structures nondestructively. ( C) 2000 American Vacuum Society. [S0734-2101(00)05302-1].