Characterization of N-type and P-type Aluminum Antimonides on Si substrates for room-temperature optoelectronic devices

To develop Aluminum Antimonide (AlSb) -based optoelectronic devices on Si substrates, AlSb films were investigated for a good crystalline quality and suitable optical and electrical properties. Under an optimized growth condition by RF-magnetron sputtering technique, the AlSb films were grown at a sputtering power of 250 W and a pressure of 0.01 mbar in argon atmosphere and a precursor Al:Sb ratio of about 88:12. The undoped AlSb films were found to have a cubic crystal structure with (111) preferred orientation and a lattice constant of 5.9985 Å under compressive strain. For the doped AlSb samples with optimized doping contents, the AlSb:Si and AlSb:Cu films with higher compressive strain were found to have a smaller lattice constant of 5.9588 Å and 5.9667 Å, respectively. Raman spectroscopy indicated strain states and lower crystalline quality induced by doping. The optical properties, analyzed by UV-Vis spectrophotometry, showed that the undoped AlSb film was transparent to IR at around 850 nm, where the doped films were transparent to IR at longer wavelengths. To evaluate the electrical properties of the AlSb films, n-type AlSb:Cu and p-type AlSb:Si films were characterized by Hall-Effect measurements. To develop AlSb-based optoelectronic devices, a PIN diode structure was grown on Si substrate. The smooth interfaces between the AlSb layers and with Si substrate were confirmed by cross-sectional TEM micrographs. Finally, I-V measurements showed diode characteristics with a turn-on voltage of about + 1.5 V for forward bias and −0.5 V for reverse bias. In summary, the AlSb-based diode structure on Si substrate had been successfully fabricated by optimized sputtering deposition. This is promising for future development of the AlSb-based optoelectronic devices.