Rare earth doped high barrier height Schottky devices

Intrinsic semiconductor epilayer are frequently adopted in power devices to increase their BV and decrease their leakage current. High purity Pr2O3-ad ded GaAs liquid phase epitaxial layers are grown with low background carrie r concentrations. Their surface chemical structures are investigated by usi ng X-ray photoelectron spectroscopy. As the surface oxidation is lowered, t hese (Au, Ag, Ni, Pt)/GaAs Schottky structures all show an improved diode p roperty by addition of Pr2O3. The resulting barrier height and ideality fac tor can be as high as 0.94 +/- 0.02 eV and as unitary as 1.03 +/- 0.01, res pectively. A leakage current of around 0.7 x 10(-6) A and a breakdown volta ge of 140 V is also obtained. These grown SDs were also irradiated by gamma -ray for the study of radiation hardness. After 4 h irradiation, all sample s are out of function at beginning. However, 4 h latter, because of the nat ure annealing, the SBH of those added samples can recover to 72% of their o riginal SBH values. Further, another 24 h past, the tendency of recovery is saturated and a 19% SBH retard is still left. During this period, the appr opriate Pr2O3-added SDs show out better radiation hardness property with co mpare to the unadded one. (C) 1999 Elsevier Science Ltd. All rights reserve d.