In the last few years there has been an explosive development in material science. It began with the theoretical prediction of a new class of three dimensional (3D) topological insulators (TIs) which are fully gapped in the bulk, but with unusual gapless ‘protected’ 2D Dirac surface states. The protection arises from the linear energy-momentum dispersion, with the surface states near the Fermi surface residing on a single “massless” Dirac cone with locked spins. If realized, these systems could be the Holy Grail in the fields of spintronics and fault-tolerant quantum computing. However, access to this 2D quantum matter is a challenge, due to the difficulty of separating surface contribution from the non-zero conductivity of the bulk. In approaches taken thus far, such as nanostructured synthesis/growth, doping, compositional tuning, or band-gap engineering via device gating, complete suppression of the bulk conduction in TIs has not yet been realized. We propose a new approach, which consists of using controlled disorder to create stable charged point defects in the bulk of topological insulators by particle irradiation in order to compensate for the “intrinsic” charged defects and to achieve a fully insulating bulk. Using swift (<3 MeV range) electron or proton beams we will create simple, vacancy and interstitial type defects that will enable us to (a) tune the bulk carrier density, thereby tuning the Fermi level across the Dirac point, and (b) to reduce bulk conductivity by creating Anderson localization. The first objective will give rise to charge compensation in a bulk TI, while the second will enable us to test recent theoretical predictions of Quantized Anomalous Hall Effect (QAHE). Identification of bulk and surface contribution in irradiation-doped samples will be obtained by combination of electronic transport in high magnetic field by Shubnikov-de Haas oscillations (SdH) and Angular Resolved Photoemision Spectroscopy (ARPES). Definition of the route for fabrication of TIs with suppressed bulk conductivity is the primary goal of the project. The second goal is determination of the effect of disorder on the surface conducting states of TI’s. With the proper choice of irradiation dose, the bulk resistivity may be increased by many orders of magnitude when the chemical potential reaches the Dirac point. Using this technique we expect to further test a recent prediction of a Topological Anderson Insulator – a nontrivial quantum phase with quantized conductance obtained by introducing disorder in a metal with strong spin-orbit interaction. The third goal of the project is fabrication by proton implantation of p-n-p or n-p-n structures below the surface of TI’s. Such structures, if realized and properly contacted, are the prototype of a tunable spintronic device that may open a path for novel applications. This proposal is an international collaboration between two groups at Ecole Polytechnique in Palaiseau, and at Orsay University, France, with unique expertise in swift particle irradiation techniques and femtosecond ARPES with the consortium lead by condensed matter physics group of the City College of New York (CCNY) -CUNY. This collaboration combines the complementary technical strengths of material science with particle beam technology to control and tune key electronic properties of the newly discovered functional class of materials.