Effect of proton irradiation on electric properties in AlGaAs/GaAs heterostructure materials

The AlGaAs/GaAs heterostructure material used for high electron mobility transistor (HEMT) has been irradiated by protons with energy from 60 to 115 keV and particle fluence from 1×1013 to 1×1015 cm−2. The changes in electric transport behavior of two-dimensional electron gas (2DEG) are shown to be dependent on the energy and the fluence of the proton. It is found that the electron mobility μ is decreased approximately 65% at a fluence of 1×1013 cm−2 and shows a linear response to the fluence, until the fluence reaches 5×1014 cm−2, and then it shows a tendency toward saturation. The saturated value of Δμ/μ0 is approximately 85%. The carrier concentration n varies with mobility, and at a proton energy of 60 keV and fluence of 1×1013 cm−2, the concentration is reduced to 95%. As the concentration of carrier diminishes, the resistance of materials increases by two or three orders of magnitude at room temperature and increases even more sharply at 77 K. Annealing experiments were carried out after irradiation. The electric properties of materials could not be restored after annealing. Therefore, the electric properties of HEMT material are degenerated by proton irradiation. The threshold value of proton energy and the fluence are given. The defects induced by proton irradiation were measured by DLTS. The activation energy, capture cross-section and defect concentration were determined.