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 was studied by Raman scattering measurements. The carrier concentration in the InGaAs channel was found to increase when the doping concentration in the donor layer was increased assuming that the donors are fully ionized. The coupled mode between the InGaAs longitudinal optical phonons and the electrons 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 between the observed Raman shift with the carrier concentration in the channel layer can be used to characterize the HEMT structures nondestructively.