Determination of electron penetration depth and stopping power of amorphous AlN using luminescence of Tm and Ho ions

Electron penetration depth and stopping power of amorphous AlN is determined using luminescence of Tm$^{+3}$ and Ho$^{+3}$ ions. Thin film bilayers of AlN:Ho and AlN:Tm are deposited on flat Silicon substrates by RF Magnetron sputtering at liquid nitrogen temperatures. In making a bilayer, 15.3 nm thick AlN:Ho film is first deposited on a flat Si(111) substrate of 2$\times $2 cm$^{2}$ surface area. On the top of this AlN:Ho film 37.8 nm thick AlN:Tm film is deposited to make it a bilayer. Electron beam of different energies, obtained from electron gun of the CL apparatus, is allowed to penetrate in the AlN:Tm/AlN:Ho bilayer film. Blue emission from Tm$^{+3}$ as a result from $^{1}$D$_{2} \quad \to \quad ^{3}$F$_{4}$ transition and green emission from Ho$^{+3}$ as a result from $^{5}$S$_{2} \quad \to \quad ^{5}$I$_{8}$ transition were used to track the electron beam penetrating in the bilayer. Energy of the beam just crossing 37.8 nm AlN:Tm film is recorded to obtain the stopping power experimentally. Experimental results are compared to the theoretical value using the established mathematical equations for stopping power. A percent deviation of 6.6{\%} is found in the experimental and theoretical results.