The Legal Aspect of Waste Management in Cameroon with Focus on the Buea Municipality

Waste production remains an inevitable part of human activity on earth. The history of waste reveals that high levels of urbanisation, sustained urban growth and increasing residential neighbourhoods remain commensurate to poor sanitation and quality of life if proper measures are not taken. This paper therefore examines the legal practices involved in waste management and to understand the challenges faced as well as propose solutions towards an improved waste management system. The work constitutes mainly secondary source data that includes the existing laws on waste management in Cameroon and other documents relating to waste from different ministries. The residents of Buea and workers of the waste management company were interviewed to get their views on waste management in Buea. Also, field observations were made to compare results with field realities. The collected data was analysed using the content analysis and descriptive techniques. Results obtained proved that there exist well stated laws for waste management in Cameroon. However, there is poor implementation of the existing laws with evidence of waste littering within neighbourhoods and along the streets. This study concludes that there should be proper sensitization of the public about existing laws and to strengthen the waste management process with use of the laws. An all-integrated approach with active community participation was recommended as a way out towards sustainable waste management in Buea.

Germanium tin: silicon photonics toward the mid-infrared [Invited]

Germanium tin(GeSn)is a group IV semiconductor with a direct band-to-band transition below 0.8 eV.Nonequilibrium GeSn alloys up to 20%Sn content were realized with low temperature(160℃)molecular beam epitaxy.Photodetectors and light emitting diodes(LEDs)were realized from in situ doped pin junctions in GeSn on Ge virtual substrates.The detection wavelength for infrared radiation was extended to 2μm with clear potential for further extension into the mid-infrared.GeSn LEDs with Sn content of up to 4%exhibit light emission from the direct band transition,although GeSn with low Sn content is an indirect semiconductor.The photon emission energies span the region between 0.81 and 0.65 eV.Optical characterization techniques such as ellipsometry,in situ reflectometry,and Raman spectroscopy were used to monitor the Sn incorporation in GeSn epitaxy.

Direct band gap luminescence from Ge on Si pin diodes

Germanium （Ge） pin photodiodes show clear direct band gap emission at room temperature, as grown on bulk silicon in both photoluminescence （PL） and electro- luminescence （EL）. PL stems from the top contact layer with highly doped Ge because of strong absorption of visible laser light excitation （532 nm）. EL stems from the recombination of injected carriers in the undoped intrinsic layer. The difference in peak positions for PL （0.73 eV） and EL （0.80 eV） is explained by band gap narrowing from high doping in n＋-top layer. A superlinear increase of EL with current density is explained by a rising ratio of direct/ indirect electron densities when quasi Fermi energy level rises into the conduction band. An analytical model for the direct/indirect electron density ratio is given using simplifying assumptions.