The authors present heavy-ion and proton upset measurements, including total dose and displacement damage, on a one-micron, GaAs, complementary-heterostructure insulated-gate FET (C-HIGFET) 1k*1k static random-access memory (SRAM). Single event upset (SEU) characteristics show a two-order-of-magnitude improvement over GaAs MESFET technology. Heavy-ion upset equilibrium measurements show that all cells upset with equal probability at the 5% linear energy transfer (LET) threshold. This indicates that for this device the shape of the cross section versus LET curve is a result of a probability distribution that applies to all cells and is not the result of variations in cell sensitivities. The data set also indicates that the traditional two-dimensional cos( theta ) normalization to LET and fluence is not applicable to this technology. >