PAMBE grown InN layers electrical conduction by low frequency noise technique

In the past decade, InN has emerged as a promising can didate for high speed electronic and optoelectronic applications up to terahertz frequencies. It is well known that the presence of surface electron accumulation in InN layers is still an important limitation to device applications. However recent reports stated the accessibility of this bulk electrical conductivity, but there exists a discrepancy between the estimated and real ones. In our work, we have explored this issue using low frequency noise measurements on Plasma - Assisted Molecular Beam Epitaxy( PAMBE ) InN layers. The quality of these layers was checked by low frequency noise measurements. The observed noise levels are in the same range as in conventional group III semiconductors such as GaAs, InAs which are presently used in high frequency devices. These results indicate that the investigated nN layers are promising for use in electronic devices. The 1/f noise temperature behaviour showed that there exist a number of charge carrier fluctuations which indicates that a part of electrical conduction takes place at the surface, which is coherent with the well known electron accumulation layer. We evidenced a transition from semiconducting behaviour to metal like conduction above 130 K, irrespective of In or N rich growth conditions. Moreover, the 1/f noise trend versus temperature indicates that the surface conduction is dominant above 100 K. Apart from surface conduction; there is an additional electrical contribution, which is dominant below 100K. This corresponds to bulk electrical conductivity which is not easily accessed by conventional electrical methods in InN