# Construct a semilogarithmic plot

• davelandsman
In summary, the semilogarithmic plot for Si doped with 2X10^15 donors/cm3 and having 4x10^14 EHP/cm^3 created uniformly at t=0. should be constructed, and the recombination coefficient alphar should be calculated for the low-level ecitation described in problem 1. If the voltage is then increased to 100,000V, what is the new current?
davelandsman
How do you solve the following problems? Thank you for any inputs.

1.Construct a semilogarithmic plot for Si doped with 2X10^15 donors/cm3 and having 4x10^14 EHP/cm^3 created uniformly at t=0. assume that tn = tp = 5us.

2.calcualte the recombination coefficient alphar for the low-level ecitation described in problem 1. assume that this value of alphar applied when the GaAs sample isuniformly exposed to a steady state optical generation rate gop = 10^19 EHP/cm^3-s. find the stead state excess carrier concentration.

3. For a 2cm long doped Si bar with a cross sectional area = 0.05 cm^2. what is the current ifwe apply 10V across it? if we generate 10^20 electron-hole pairs per second per cm^3 uniformaly in the bar and the lifetime tn = tp = 10^-4s, what is the new current? assume the low-level alphar doesn't change for high-level injection. if the voltage is then increased to 100,000V, what is the new current? Assume up=500cm^2/Vs, but you must choose the appropriate value for electrons.

4. A 100 mW laser beam with wavelength = 6328 is focused onto a GaAs sample 100um thick. the absorption coefficient at this ewavelength is 2X10^4 cm^-1. find the number of photons emitted per second by radiative recombination in the GaAs, assuming perfect quantum efficiency. what power is delivered to the sample as heat?

Thank you.

Thank you for your help. I have another question about a Si sample that is uniformly optically excited at room temp.:
A Si sample with 10^15/cm^3 donors is uniformly optically excited at room temperature such that 10^19/cm^3 electron-hole pairs are generated per second. Find the separation of the quasi-Fermi levels and the change of conductivity upon shining the light. Electron and hole lifetimes are both 10us. Dp = 12 cm^2/s.

Thank you.

You're not supposed to just do people's homework for them. Just give a hint or a partial solution and only do that if they show their own work.

I'm locking this thread. kobetsai, as Orthodontist says, the PF homework forum guidelines are pretty clear about how to help people. Please re-read them to be sure that you understand. We are here as tutors, not as homework solution machines. davelandsman, as Ortho says, you need to show your work so far when you post homework questions.

Welcome to PF to both of you. It can be a great resource when used correctly.

The complete solutions have been deleted, and I reopened the thread so you can get proper help with your homework.

As berkeman stated, we offer HELP, not complete answers. Handing someone a complete solution will not help them understand the subject and learn how to do it themself. If you do not know a way to prompt them in the right direction without giving away the complete answer, please don't respond.

## 1. What is a semilogarithmic plot?

A semilogarithmic plot is a graph that uses a logarithmic scale for one of its axes and a linear scale for the other. This allows for a large range of data to be plotted in a more compact and visually clear way.

## 2. How do I construct a semilogarithmic plot?

To construct a semilogarithmic plot, you will need to have data points that cover a wide range of values. Then, choose which axis will have the logarithmic scale and plot your data accordingly. Finally, label your axes and add a title to your graph.

## 3. What are the benefits of using a semilogarithmic plot?

A semilogarithmic plot is useful for visualizing data that covers a wide range of values, as it allows for a better understanding of the overall trend and patterns. It also helps to highlight smaller changes in data that may be overshadowed in a linear plot.

## 4. When should I use a semilogarithmic plot?

A semilogarithmic plot is typically used when the data being plotted has a large range of values, or when the data follows an exponential or power law relationship. It can also be used to show the growth or decay of a quantity over time.

## 5. Can I create a semilogarithmic plot using software?

Yes, there are many software programs that allow you to easily create semilogarithmic plots, such as Microsoft Excel, MATLAB, and Python. These programs have built-in functions for creating logarithmic axes and plotting data accordingly.

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