Generating a raw transaction using ethers.js

gistfile.js

var ethers = require('ethers');
var Wallet = ethers.Wallet;
var utils = ethers.utils;
var privateKey = '<privatekey>'
var wallet = new ethers.Wallet(privateKey);

var transaction = {
    // needs to be greater than the nonce of the previous tx
    // from this wallet
    // can skip values
    nonce: 1393251,
    gasLimit: 21000,
    gasPrice: utils.bigNumberify("20000000000"),

    to: "0x9fa69Ec8D66fE3988b8f187C8F5cE2c5cCe95Ebd",

    value: utils.parseEther("0.0001"),

    // optional
    data: "0x",

    // This ensures the transaction cannot be replayed on different networks
    // ropsten network
    chainId: 3
};

var signedTransaction = wallet.sign(transaction);
console.log(signedTransaction)
// this will console out the raw transaction which can then be broadcasted on
// etherscan etc