The Crystal Structure Damage Effects Of InP And GaN Induced By Energetic Heavy Ions

The rapid developments of semiconductor industry promote the upgrading of semiconductor devices and materials, including the development of the first generation of silicon. Though the development of silicon devices is quite mature, it also faces to enormous challenges due to that the silicon belongs to indirect band gap semiconductor with low light-emitting efficiency and the size of the device is limited by photolithographic techniques. At the same time, the development of second and third generations of semiconductor represented by the In P and Ga N, respectively, have been attracting tremendous attentions. In P is direct band gap semiconductor, with high electron mobility and good resistance to radiation. It is widely used in the preparation of high frequency, high speed microwave devices and solar cells applied in space. In addition, In P is also considered as one of the most competitive candidate as a substrate material in the optical fiber communication field with high digital rate and good monochromaticity. Ga N is a typical wide bandgap semiconductor with strong breakdown field and good thermal conductivity. It is suit for manufacturing high power microelectronic devices, mainly used in high temperature, high pressure conditions and irradiation extreme conditions. Energetic heavy ion irradiation induces lattice atom displacement, resulting in defects and disturbance which would further lead to the physical and chemical properties and even have a serious influence on the reliability of the device. In P and Ga N as the new type of semiconductor material have excellent electrical, thermal and optical properties. They are the foundation for the development of the electronic device and photoelectric device. The irradiation effects of research on In P and Ga N for radiation-hardened reinforcement of semiconductor devices is of great guiding significance and provide the reference for the use of the device, It can also broaden the application of these two kinds of materials in aerospace and military industry.In this dissertation, high quality In P and Ga N samples were successfully fabricated by liquid encapsulated czochralski technique(LEC) and hydride vapor phase epitaxy technique(HVPE), respectively. Swift heavy ions(SHIs) 209 Bi and 86 Kr with energy of 2 Ge V provided by the HIRFL accelerator and highly charged ions(HCIs) Krq+ and Xe q+ with energy of 1.4 Me V offered by 320 k V high-voltage platform of IMP were used to do irradiation experiment on In P and Ga N samples. After irradiation, the samples were investigated by Raman spectrometer and transmission electron microscopy. The samples were irradiated by SHIs with varying electronic energy loss(d E/dx)e, ion fluences and other parameters in the experiments to carry out a systematic study of lattice vibration modes changes induced by structure damages and the latent tracks formation with the(d E/dx)e and ion fluences.SHI irradiation experiment results show that, after irradiated by SHIs, the latent tracks are observed on the surface of In P samples when the(d E/dx)e value reached 13 ke V/nm. There also observed polycrystalline tracks with suborbicular cross-section on the surface of In P samples and amorphous tracks with a longitudinal section like a strip in the bulk after irradiated by 209 Bi for 30 ke V/nm(d E/dx)e value. There observed the red shift of LO mode in In P samples after irradiated by 209 Bi and 86 Kr ions. A maximum peak shift of 2.2 cm-1 was observed for 12.7 ke V/nm(d E/dx)e value at a fluence of 1×1011 ions/cm2 whereas a maximum peak shift of 7.6 cm-1 was observed at the fluence of 3.6×1012 ions/cm2 induced by Bi ions irradiation for 31.4 ke V/nm(d E/dx)e value with the characteristic peaks appeard asymmetric broadening. The observed Raman shifts reveal the presence of tensile stress, which increases with increasing(d E/dx)e and ion fluence.The latent tracks are also observed in the Ga N samples irradiated with 209 Bi ions by cross-sectional TEM images. The lattice fringes in tracks are rather vague, but not completely disappeared, so there is no formation of amorphous. Moreover, there is no latent tracks formation in samples after irradiated by 86 Kr ions. And the Raman spectra show that, the intensity of the Raman peaks sharply decline with increasing ion fluences in Ga N samples for 19 ke V/nm(d E/dx)e value, but the peak position hardly changed. However there appeared the blue shift of E2(high) mode while the red shift of A1(LO) mode in Ga N samples when the(d E/dx)e value reached 46 ke V/nm. The compressive stress increases with increasing(d E/dx)e and fluence.HCI irradiation experiments results show that the suborbicular latent tracks with a lattice fringe were induced on the surface of In P samples by TEM images, though the track peripheral region was hardly observed lattice stripes. The red shift of LO mode in In P samples were observed after irradiated by HCIs, the Raman shift becomes more obvious with increasing fluence and then the Raman peaks disappeared at the fluence of 1×1013 ions/cm2, which suggests that the crystallinity of In P was deteriorated and resulted in the amorphous nature of the samples. While there no latent track was observed on the surface of the Ga N samples after irradiated by HCIs. The Raman spectroscopy show that, the intensity of the Raman peaks in Ga N samples decreased gradually with the ion fluence increasing, while the peaks hardly moved.Finally, we compared to analyze the results of SHI irradiation experiments. After irradiated by SHIs, there observed small variation of the phonon modes in Ga N crystal at higher(d E/dx)e whereas the larger Raman shifts in In P samples even at the lower(d E/dx)e values with increasing ion fluences. What is more, there formed amorphous in tracks of In P samples and with a little changes in Ga N. Both of HCI and SHI irradiation experiments reach the same conclusion that In P crystal is easier to introduce the impurities and defects under the similar irradiation environment, leading to the disorder of the crystal structure.