In the dynamic landscape of semiconductor research，germanium has captured global attention as a promising alternative to silicon in the past two decades^［1］. Boasting distinct advantages over silicon，including enhanced electron and hole mobility along with a smaller band gap，germanium is poised to play a pivotal role in shaping the evolution of upcoming optoelectronic devices^［2-3］. Its applications extend to ionizing radiation detectors，infrared（IR）photodetectors，optical components，and temperature sensors^［4-5］. Notably，compared to silicon，germanium's reduced band gap enables efficient absorption and response to extended wavelengths of infrared radiation，establishing it as a key contributor to the advancement of sophisticated IR devices. Blocked-impurity-band（BIB）detectors，doped with arsenic（Si：As）or antimony（Si：Sb）have been utilized on the Spitzer Space Telescope and James Webb Space Telescope（JWST）for detecting wavelengths in the 5 to 40 µm range^［6，7］. Whereas，germanium doped with shallow impurity can be used as a BIB detector responsive to longer wavelengths，up to 200 μm^［8］. Boron stands out as the optimal choice for introducing shallow energy levels^［9］. The most widely used technique to dope semiconductors in ion implantation is due to its good control of the dopant concentration and profile，and the isotopic purity of the implanted species^［10］. By changing the impurity concentration of ion implantation，the height of the interface barrier in the BIB detector can be adjusted，significantly reducing the dark current，which can be controlled at the order of ${\mathrm{10}}^{-\mathrm{10}}$A^［11-12］. One of the critical challenges associated with ion implantation is the inadvertent creation of damage to the crystal lattice. This damage encompasses a spectrum of defects，ranging from simple point defects like vacancies and self-interstitials to more complex structures such as small and large defect clusters，and in extreme cases，fully amorphous layers of material. These structural anomalies introduce electronic（deep）levels within the semiconductor band gap，leading to alterations in the material's electrical properties^［13］. This can further be the cause of dark currents and can affect the detector’s sensitivity and detectivity. So，the study of a better understanding of lattice damage in the material is very crucial.

Contrary to silicon，there is a scarcity of comprehensive studies on lattice damage in germanium resulting from ion implantation using boron as a dopant. Until now，very few reports have been available on the study of lattice damage in germanium by boron implantation. Suresh et al.（2001）provided noticeable insights into the diffusion behavior of boron in germanium after implantation by employing secondary ion mass spectroscopy（SIMS）^［14］.^{Later，Yong et al.（2005）studied the effect of high concentration on the electrical and chemical properties of boron-implanted germanium［15］. However，a thorough exploration into the nuances of the lattice damage process resulting from implantation has yet to be undertaken. Inspired by a gap in understanding，the purpose of this research is to explore the mechanism and effects of boron implantation-induced lattice damage in germanium.}

The process involved implanting Boron ions into undoped germanium wafers with a <100> orientation at room temperature. The boron ions，carrying an energy of 80 keV，were implanted at six different doses ranging from 1×10¹³ to 3×10¹⁵cm^-2. The incident beam was inclined at an angle of 7 degrees off the surface normal. After the initial implantation of samples，X-ray diffraction（XRD）and Raman spectroscopy were employed on as implanted samples to analyze the structural alterations and lattice damage.

Furthermore，the samples underwent annealing at 450 degrees and subsequently examined through X-ray photoelectron spectroscopy（XPS）and SIMS in conjunction with the previously employed XRD and Raman spectroscopy techniques for a better understanding of chemical and structural changes that happened after annealing. The results revealed that the defects induced by the implantation process were predominantly eliminated after the thermal treatment except the strain residual which still exists at high doses showcasing the irreversible damage caused by ion implantation at higher doses.

To explore and confirm the alterations in the crystal lattice resulting from boron ion implantation in germanium Ge，X-ray diffraction（XRD）was conducted along the（100）crystallographic direction. The objective was to systematically examine the diffraction patterns across a series of samples，encompassing a spectrum of boron doses ranging from 1×10¹³ to 3×10¹⁵ cm^-2. Samples were examined after implantation and annealing，to study the comprehensive impact of ion implantation on the germanium crystal lattice. Fig. 1（a）shows the spectra of as-implanted samples，it was observed that，for the majority of boron doses，there were no significant deviations in the peak positions or broadening of diffraction peaks. However，at doses of 1×10¹⁴ and 5×10¹⁴ cm^-2，a slight broadening of the peak was noted，suggesting the occurrence of lattice distortions such as point defects resulting from the implantation at these doses. Additionally，for the highest dose of 3×10¹⁵ cm^-2，a distinct shoulder peak appeared on the left side，indicating the presence of compressive strain caused by lattice damage. This observation aligns well with findings reported by Yong in implanted Ge at a boron dose 3×10¹⁶cm^-2［13］，confirming the evidence of lattice damage-induced strain as the implantation dose increases.

However，post-annealing has mitigated some distortions in all spectra yet the widest peaks persist for the highest boron dose，even after annealing that occurs at 450 °C for 60 s. Fig. 1（b）shows the result after annealing. We can clearly see that there are no additional peaks of any intensity but there is still of broadening of the peaks exists for high doses. This peak broadening is the maximum for the highest dose of 3×10¹⁵ cm^-2，which can be attributed to the implantation-induced irreversible strain.

Raman spectroscopy was implied on the implanted germanium to further analyze the structural properties of boron implanted germanium. In Fig. 2，changes in Raman peak positions and intensities were observed，reflecting alterations in the germanium lattice's vibrational modes due to boron implantation. Fig. 2（a）shows the Raman spectra of the as-implanted p-type Ge samples. In observations，a distinct peak was noted around 300cm^-1 in the Raman spectra，which can be attributed to pristine germanium crystal^［16］. There were tiny peaks of negligible intensities were observed for some doses，indication of distortion in crystal lattice structure，similar to the findings of K. P. Jain in the Raman scattering analysis of ion-implanted silicon^［17］. Furthermore，for doses up to 1×10¹⁵ and 5×10¹⁴ cm^-2，the spectra displayed a minor shift of 1cm^-1，∆ω = ω_observed – ω_pristine.

However，a significant deviation was observed at the highest dose of 3×10¹⁵ cm^-2 where a major Raman shift of 132 cm^-1 was observed，as shown in the Fig. 3. This deviation indicates a substantial alteration in the vibrational characteristics of the material，potentially due to strain produced by the higher dose of the implanted material. It’s worth to note here that at higher doses intensity of peaks has also decreased.This further confirms the presence of lattice strain in the sample at these higher doses，and the same trend was observed by Sh.B. Utamuradova in Si samples irritated by protons^［18］. This analysis shows a good agreement with XRD results. Fig. 2（b）shows Raman spectra after annealing of the samples at 450^{°C for 60s. The spectra reveal a distinct lack of additional peaks and discernible peak shifts. The absence of peak shifts and additional peaks in the germanium Raman spectra indicates successful restoration of the crystal lattice，minimizing ion-induced distortions. However，the observation of the lowest intensity for some doses even after annealing indicates that some residual effects or modifications persist in the material，persistent with the findings of XRD results.}

To explore the influence of implantation on elemental and chemical alterations at the sample's surface after annealing，X-ray photoelectron spectroscopy（XPS）was performed on all annealed samples. Fig. 4 illustrates complete Ge3d scan and C1scan of pure germanium and post- annealed boron implanted germanium samples. In the Ge3d spectra of Fig. 4（a），a clear shift from pristine Ge（29.3eV）peak^［19］ is observed that shows successful introduction of boron at the sample surface.

Slight differences in peak shifts across the six samples were observed，this point towards potential structural changes induced by boron incorporation. Particularly，a distinctive feature emerged with a significant decrease in peak intensity for samples exposed to doses of 3×10¹⁵ and 5×10¹⁴ cm^-2. This reduction in intensity even after annealing suggests presence of strain produced into the lattice structure by boron incorporation. This result is consistent with the results of XRD and Raman analysis. Fig. 5 illustrates the high resolution B1s scan for each distinct dose. The peak analysis was performed using Gaussian fitting. The peak that consistently appears within the energy range of 181 to 184 electron volts（eV），signifying the presence characteristic binding energy associated with boron present in the germanium lattice. The presence of satellite peaks appearing in all spectra further indicates the existence of various chemical states which lead to the formation of boron oxides within the samples，as expected in implanted materials. This is analogus to what was observed by Zhihai Cai in studying the influence of boron implantation into silicon substrate^［20］. Additionally，for B1 spectra of the highest dose 3×10¹⁵cm^-2，there is a shift in oxidation state of boron is observed. The observed shift in oxidation state in the XPS spectra can be correlated with the lattice damage and strain induced by ion implantation at high dose. The introduction of ions into the lattice structure leads to point defects and residual strain，affecting the electronic configuration of the material. This，in turn，manifests as a shift in the oxidation state，reflecting alterations in the chemical environment and bonding configurations caused by the implantation process. This further confirms our findings of XRD and Raman analysis.

In order to further clarify the results obtained from XRD，Raman spectroscopy，and XPS analyses，secondary ion mass spectrometry（SIMS）was employed specifically on samples subjected to two higher doses. This additional SIMS analysis aimed to provide comprehensive insights into the elemental distribution，composition，and depth profiling，enhancing our understanding of the structural and chemical modifications induced by the implantation of elevated doses which are 5×10¹⁴cm^-2 and 3×10¹⁵cm^-2. Fig. 6 shows the distribution of boron within the germanium lattice，providing insights into the implantation depth and concentration. Table 1 presents key findings，highlighting relevant data on boron concentration within the germanium samples.

Notably，the projected depth R_p，as revealed by the SIMS depth profile for both doses，measures approximately 0.239 μm. This uniformity in depth signifies a robust control over the implantation process，emphasizing its reproducibility. Additionally，a slight channeling tail has been observed for both doses. The observed channeling tail in this analysis aligns with the close link between the channeling effect and lattice damage in ion implantation. Channeling concentrates ion flux and induces localized strain and defects. This interplay is vital for understanding the ion penetration and distribution within the crystalline lattice，germanium's high stopping power further amplifies these effects. This observation is in agreement with the findings of a previous study conducted by R. Wittmann who studied depth profiles for boron implanted germanium for the energy range from 5 to 40 keV^［21］.

Boron ion implantation effects on the lattice structure of pure germanium crystals were investigated using 80 keV energy and fluencies spanning from 1×10¹³ to 3×10¹⁵cm^-2. This study employed a multi-technique approach，integrating X-ray diffraction（XRD），Raman spectroscopy，X-ray photoelectron spectroscopy（XPS），and secondary ion mass spectrometry（SIMS）to comprehensively analyze the structural and chemical alterations induced by boron ion implantation at these specified doses. In all cases，minimal distortions were observed at lower doses of boron ion implantation，which went away after annealing at 450 °C for 60 s，as evidenced by the comprehensive analysis by XRD and Raman spectroscopy. However，for higher doses，the study identified presence of potential residual lattice distortion，emphasizing the challenges of mitigating irreversible distortions during implantation. Residual strain due to lattice damage at high doses was confirmed from XPS and SIMS analysis. In conclusion，this research contributes valuable insights into the lattice damage induced by boron ion implantation in germanium，emphasizing the importance of understanding and mitigating these effects for the development of high-performance semiconductor devices.