We report on the first unambiguous observation of macroscopic quantum tunneling (MQT) in a single submicron Bi(2)Sr(2)CaCu(2)O(8+delta) surface intrinsic Josephson junction (IJJ) by measuring its temperature-dependent switching current distribution. All relevant junction parameters were determined in situ in the classical regime and were used to predict the behavior of the IJJ in the quantum regime via MQT theory. Experimental results agree quantitatively with the theoretical predictions, thus confirming the MQT picture. Furthermore, the data also indicate that the surface IJJ, where the current flows along the c axis of the crystal, has the conventional sinphi current-phase relationship.

The self-heating effect on intrinsic tunneling spectra ͑ITSs͒ is investigated using stacks of intrinsic Josephson junctions ͑IJJs͒ in near optimally doped Bi 2 Sr 2 CaCu 2 O 8+␦ crystals. The area of the stacks S ranges from 12 down to 0.16 m 2 . For IJJs with larger S, ITSs are distorted by self-heating, but become progressively less size dependent as S decreases down to submicrometer level. Analysis based on the ballistic phonon model of Krasnov et al. indicates a temperature rise of ϳ5 K for the smallest junctions at the bias voltage corresponding to the conductance peak. A brief comparison between the ITSs and spectra from other techniques is presented.

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