A homogeneous p-n junction diode by selective doping of few layer MoSe using ultraviolet ozone for high-performance photovoltaic devices.

The realization of p-n homojunctions, which can be achieved via spatially controlled carrier-type modulation, remains a challenge for two-dimensional transition metal dichalcogenides. Here, we report an effective method to tune intrinsic n-type few-layer MoSe to p-type through controlling precisely the ultraviolet-ozone treatment time, which can be attributed to the surface charge transfer from the underlying MoSe to MoO (x < 3). The resulting hole mobility and concentration are ∼20.1 cm V s and ∼1.9 × 10 cm, respectively, and the on-off ratio is ∼10, which are comparable to the values of pristine n-type MoSe. Moreover, the lateral p-n homojunction prepared by partially treating MoSe displays a high rectification ratio of 2.4 × 10, an ideality factor of 1.1, and a high photoresponsivity of 0.23 A W to the 633 nm laser at V = 0 V and V = 0 V due to the built-in potential in the p-n homojunction area. Our findings ensure the MoSe p-n diode as a promising candidate for future low-power operating photodevices.