The temperature dependence of the tube morphology and the lateral piezoresponse measured in situ on as-grown horizontal tubes are presented in detail in Fig. 3. The topog- raphy and PFM signal were followed while the tube sample was slowly heated in the PFM setup. We found that the to- pography of the tubes does not change until 100 C, and only at temperatures close to 150 C do the tubes contract by about 10% to 12% relative to their initial height. This finding confirms the occurrence of some structural changes; how- ever, no collapsing of the tubes or integrity loss were docu- mented in our experimental conditions, in contrast to a recent study by Sedman et al