GaInP/GaAs triple barrier resonant tunneling diodes (TBRTDs) grown by metal organic chemical vapor deposition were fabricated. Temperature dependence of current-voltage characteristics was measured from 18.6 to 294.1 K and negative differential resistance was observed up to 167 K. From the temperature dependence of peak voltage, peak current, valley voltage, and valley current, we estimated that the NDR characteristic of the TBRTDs is due to alignment and misalignment of quantum levels of left and right well at energy close to the conduction band bottom. (C) 2003 Elsevier Science B.V. All rights reserved.